@article{FigueiredoKraussSteffanDewenteretal.2019, author = {Figueiredo, Ludmilla and Krauss, Jochen and Steffan-Dewenter, Ingolf and Cabral, Juliano Sarmento}, title = {Understanding extinction debts: spatio-temporal scales, mechanisms and a roadmap for future research}, series = {Ecography}, volume = {42}, journal = {Ecography}, number = {12}, doi = {10.1111/ecog.04740}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204859}, pages = {1973-1990}, year = {2019}, abstract = {Extinction debt refers to delayed species extinctions expected as a consequence of ecosystem perturbation. Quantifying such extinctions and investigating long-term consequences of perturbations has proven challenging, because perturbations are not isolated and occur across various spatial and temporal scales, from local habitat losses to global warming. Additionally, the relative importance of eco-evolutionary processes varies across scales, because levels of ecological organization, i.e. individuals, (meta)populations and (meta)communities, respond hierarchically to perturbations. To summarize our current knowledge of the scales and mechanisms influencing extinction debts, we reviewed recent empirical, theoretical and methodological studies addressing either the spatio-temporal scales of extinction debts or the eco-evolutionary mechanisms delaying extinctions. Extinction debts were detected across a range of ecosystems and taxonomic groups, with estimates ranging from 9 to 90\% of current species richness. The duration over which debts have been sustained varies from 5 to 570 yr, and projections of the total period required to settle a debt can extend to 1000 yr. Reported causes of delayed extinctions are 1) life-history traits that prolong individual survival, and 2) population and metapopulation dynamics that maintain populations under deteriorated conditions. Other potential factors that may extend survival time such as microevolutionary dynamics, or delayed extinctions of interaction partners, have rarely been analyzed. Therefore, we propose a roadmap for future research with three key avenues: 1) the microevolutionary dynamics of extinction processes, 2) the disjunctive loss of interacting species and 3) the impact of multiple regimes of perturbation on the payment of debts. For their ability to integrate processes occurring at different levels of ecological organization, we highlight mechanistic simulation models as tools to address these knowledge gaps and to deepen our understanding of extinction dynamics.}, language = {en} } @article{GamezViruesPerovićGossneretal.2015, author = {G{\´a}mez-Viru{\´e}s, Sagrario and Perović, David J. and Gossner, Martin M. and B{\"o}rschig, Carmen and Bl{\"u}thgen, Nico and de Jong, Heike and Simons, Nadja K. and Klein, Alexandra-Maria and Krauss, Jochen and Maier, Gwen and Scherber, Christoph and Steckel, Juliane and Rothenw{\"o}hrer, Christoph and Steffan-Dewenter, Ingolf and Weiner, Christiane N. and Weisser, Wolfgang and Werner, Michael and Tscharntke, Teja and Westphal, Catrin}, title = {Landscape simplification filters species traits and drives biotic homogenization}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, number = {8568}, doi = {10.1038/ncomms9568}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141925}, year = {2015}, abstract = {Biodiversity loss can affect the viability of ecosystems by decreasing the ability of communities to respond to environmental change and disturbances. Agricultural intensification is a major driver of biodiversity loss and has multiple components operating at different spatial scales: from in-field management intensity to landscape-scale simplification. Here we show that landscape-level effects dominate functional community composition and can even buffer the effects of in-field management intensification on functional homogenization, and that animal communities in real-world managed landscapes show a unified response (across orders and guilds) to both landscape-scale simplification and in-field intensification. Adults and larvae with specialized feeding habits, species with shorter activity periods and relatively small body sizes are selected against in simplified landscapes with intense in-field management. Our results demonstrate that the diversity of land cover types at the landscape scale is critical for maintaining communities, which are functionally diverse, even in landscapes where in-field management intensity is high.}, language = {en} } @article{KraussGallenbergerSteffanDewenter2011, author = {Krauss, Jochen and Gallenberger, Iris and Steffan-Dewenter, Ingolf}, title = {Decreased Functional Diversity and Biological Pest Control in Conventional Compared to Organic Crop Fields}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69005}, year = {2011}, abstract = {Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields. In contrast, the abundance of cereal aphids was five times lower in organic fields, while predator abundances were three times higher and predator-prey ratios twenty times higher in organic fields, indicating a significantly higher potential for biological pest control in organic fields. Insecticide treatment in conventional fields had only a short-term effect on aphid densities while later in the season aphid abundances were even higher and predator abundances lower in treated compared to untreated conventional fields. Our data indicate that insecticide treatment kept aphid predators at low abundances throughout the season, thereby significantly reducing top-down control of aphid populations. Plant and pollinator species richness as well as predator abundances and predator-prey ratios were higher at field edges compared to field centres, highlighting the importance of field edges for ecosystem services. In conclusion organic farming increases biodiversity, including important functional groups like plants, pollinators and predators which enhance natural pest control. Preventative insecticide application in conventional fields has only short-term effects on aphid densities but long-term negative effects on biological pest control. Therefore conventional farmers should restrict insecticide applications to situations where thresholds for pest densities are reached.}, subject = {Landwirtschaft}, language = {en} } @article{CorneliusLeingaertnerHoissetal.2013, author = {Cornelius, Christine and Leing{\"a}rtner, Annette and Hoiss, Bernhard and Krauss, Jochen and Steffan-Dewenter, Ingolf and Menzel, Annette}, title = {Phenological response of grassland species to manipulative snowmelt and drought along an altitudinal gradient}, series = {Journal of Experimental Botany}, volume = {64}, journal = {Journal of Experimental Botany}, number = {1}, doi = {10.1093/jxb/ers321}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126888}, pages = {241-251}, year = {2013}, abstract = {Plant communities in the European Alps are assumed to be highly affected by climate change, as the temperature rise in this region is above the global average. It is predicted that higher temperatures will lead to advanced snowmelt dates and that the number of extreme weather events will increase. The aims of this study were to determine the impacts of extreme climatic events on flower phenology and to assess whether those impacts differed between lower and higher altitudes. In 2010, an experiment simulating advanced and delayed snowmelt as well as a drought event was conducted along an altitudinal transect approximately every 250 m (600-2000 m above sea level) in the Berchtesgaden National Park, Germany. The study showed that flower phenology was strongly affected by altitude; however, there were few effects of the manipulative treatments on flowering. The effects of advanced snowmelt were significantly greater at higher than at lower sites, but no significant difference was found between both altitudinal bands for the other treatments. The response of flower phenology to temperature declined through the season and the length of flowering duration was not significantly influenced by treatments. The stronger effect of advanced snowmelt at higher altitudes may be a response to differences in treatment intensity across the gradient. Consequently, shifts in the date of snowmelt due to global warming may affect species more at higher than at lower altitudes, as changes may be more pronounced at higher altitudes. These data indicate a rather low risk of drought events on flowering phenology in the Bavarian Alps.}, language = {en} } @article{HolzschuhDormannTscharntkeetal.2013, author = {Holzschuh, Andrea and Dormann, Carsten F. and Tscharntke, Teja and Steffan-Dewenter, Ingolf}, title = {Mass-flowering crops enhance wild bee abundance}, series = {Oecologia}, volume = {172}, journal = {Oecologia}, number = {2}, doi = {dx.doi.org/10.1007/s00442-012-2515-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126852}, pages = {447-484}, year = {2013}, abstract = {Although agricultural habitats can provide enormous amounts of food resources for pollinator species, links between agricultural and (semi-)natural habitats through dispersal and foraging movements have hardly been studied. In 67 study sites, we assessed the interactions between mass-flowering oilseed rape fields and semi-natural grasslands at different spatial scales, and their effects on the number of brood cells of a solitary cavity-nesting bee. The probability that the bee Osmia bicornis colonized trap nests in oilseed rape fields increased from 12 to 59 \% when grassland was nearby, compared to fields isolated from grassland. In grasslands, the number of brood cells of O. bicornis in trap nests was 55 \% higher when adjacent to oilseed rape compared to isolated grasslands. The percentage of oilseed rape pollen in the larval food was higher in oilseed rape fields and grasslands adjacent to oilseed rape than in isolated grasslands. In both oilseed rape fields and grasslands, the number of brood cells was positively correlated with the percentage of oilseed rape pollen in the larval food. We show that mass-flowering agricultural habitats—even when they are intensively managed—can strongly enhance the abundance of a solitary bee species nesting in nearby semi-natural habitats. Our results suggest that positive effects of agricultural habitats have been underestimated and might be very common (at least) for generalist species in landscapes consisting of a mixture of agricultural and semi-natural habitats. These effects might also have—so far overlooked—implications for interspecific competition and mutualistic interactions in semi-natural habitats.}, language = {en} } @article{SickelAnkenbrandGrimmeretal.2015, author = {Sickel, Wiebke and Ankenbrand, Markus J. and Grimmer, Gudrun and Holzschuh, Andrea and H{\"a}rtel, Stephan and Lanzen, Jonathan and Steffan-Dewenter, Ingolf and Keller, Alexander}, title = {Increased efficiency in identifying mixed pollen samples by meta-barcoding with a dual-indexing approach}, series = {BMC Ecology}, volume = {15}, journal = {BMC Ecology}, number = {20}, doi = {10.1186/s12898-015-0051-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125730}, year = {2015}, abstract = {Background Meta-barcoding of mixed pollen samples constitutes a suitable alternative to conventional pollen identification via light microscopy. Current approaches however have limitations in practicability due to low sample throughput and/or inefficient processing methods, e.g. separate steps for amplification and sample indexing. Results We thus developed a new primer-adapter design for high throughput sequencing with the Illumina technology that remedies these issues. It uses a dual-indexing strategy, where sample-specific combinations of forward and reverse identifiers attached to the barcode marker allow high sample throughput with a single sequencing run. It does not require further adapter ligation steps after amplification. We applied this protocol to 384 pollen samples collected by solitary bees and sequenced all samples together on a single Illumina MiSeq v2 flow cell. According to rarefaction curves, 2,000-3,000 high quality reads per sample were sufficient to assess the complete diversity of 95\% of the samples. We were able to detect 650 different plant taxa in total, of which 95\% were classified at the species level. Together with the laboratory protocol, we also present an update of the reference database used by the classifier software, which increases the total number of covered global plant species included in the database from 37,403 to 72,325 (93\% increase). Conclusions This study thus offers improvements for the laboratory and bioinformatical workflow to existing approaches regarding data quantity and quality as well as processing effort and cost-effectiveness. Although only tested for pollen samples, it is furthermore applicable to other research questions requiring plant identification in mixed and challenging samples.}, language = {en} } @article{HendriksmaHaertelSteffanDewenter2011, author = {Hendriksma, Harmen P. and H{\"a}rtel, Stephan and Steffan-Dewenter, Ingolf}, title = {Testing Pollen of Single and Stacked Insect-Resistant Bt-Maize on In vitro Reared Honey Bee Larvae}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {12}, doi = {10.1371/journal.pone.0028174}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137803}, pages = {e28174}, year = {2011}, abstract = {The ecologically and economic important honey bee (Apis mellifera) is a key non-target arthropod species in environmental risk assessment (ERA) of genetically modified (GM) crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops.}, language = {en} } @article{KesslerHertelJungkunstetal.2012, author = {Kessler, Michael and Hertel, Dietrich and Jungkunst, Hermann F. and Kluge, J{\"u}rgen and Abrahamczyk, Stefan and Bos, Merijn and Buchori, Damayanti and Gerold, Gerhard and Gradstein, S. Robbert and K{\"o}hler, Stefan and Leuschner, Christoph and Moser, Gerald and Pitopang, Ramadhanil and Saleh, Shahabuddin and Schulze, Christian H. and Sporn, Simone G. and Steffan-Dewenter, Ingolf and Tjitrosoedirdjo, Sri S. and Tscharntke, Teja}, title = {Can Joint Carbon and Biodiversity Management in Tropical Agroforestry Landscapes Be Optimized?}, series = {PLoS One}, volume = {7}, journal = {PLoS One}, number = {10}, doi = {10.1371/journal.pone.0047192}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132016}, pages = {e47192}, year = {2012}, abstract = {Managing ecosystems for carbon storage may also benefit biodiversity conservation, but such a potential 'win-win' scenario has not yet been assessed for tropical agroforestry landscapes. We measured above-and below-ground carbon stocks as well as the species richness of four groups of plants and eight of animals on 14 representative plots in Sulawesi, Indonesia, ranging from natural rainforest to cacao agroforests that have replaced former natural forest. The conversion of natural forests with carbon stocks of 227-362 Mg C ha\(^{-1}\) to agroforests with 82-211 Mg C ha\(^{-1}\) showed no relationships to overall biodiversity but led to a significant loss of forest-related species richness. We conclude that the conservation of the forest-related biodiversity, and to a lesser degree of carbon stocks, mainly depends on the preservation of natural forest habitats. In the three most carbon-rich agroforestry systems, carbon stocks were about 60\% of those of natural forest, suggesting that 1.6 ha of optimally managed agroforest can contribute to the conservation of carbon stocks as much as 1 ha of natural forest. However, agroforestry systems had comparatively low biodiversity, and we found no evidence for a tight link between carbon storage and biodiversity. Yet, potential win-win agroforestry management solutions include combining high shade-tree quality which favours biodiversity with cacao-yield adapted shade levels.}, language = {en} } @article{HolzschuhDormannTscharntkeetal.2013, author = {Holzschuh, Andrea and Dormann, Carsten F. and Tscharntke, Teja and Steffan-Dewenter, Ingolf}, title = {Mass-flowering crops enhance wild bee abundance}, series = {Oecologia}, volume = {172}, journal = {Oecologia}, number = {2}, doi = {10.1007/s00442-012-2515-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132149}, pages = {477-484}, year = {2013}, abstract = {Although agricultural habitats can provide enormous amounts of food resources for pollinator species, links between agricultural and (semi-)natural habitats through dispersal and foraging movements have hardly been studied. In 67 study sites, we assessed the interactions between mass-flowering oilseed rape fields and semi-natural grasslands at different spatial scales, and their effects on the number of brood cells of a solitary cavity-nesting bee. The probability that the bee Osmia bicornis colonized trap nests in oilseed rape fields increased from 12 to 59 \% when grassland was nearby, compared to fields isolated from grassland. In grasslands, the number of brood cells of O. bicornis in trap nests was 55 \% higher when adjacent to oilseed rape compared to isolated grasslands. The percentage of oilseed rape pollen in the larval food was higher in oilseed rape fields and grasslands adjacent to oilseed rape than in isolated grasslands. In both oilseed rape fields and grasslands, the number of brood cells was positively correlated with the percentage of oilseed rape pollen in the larval food. We show that mass-flowering agricultural habitats—even when they are intensively managed—can strongly enhance the abundance of a solitary bee species nesting in nearby semi-natural habitats. Our results suggest that positive effects of agricultural habitats have been underestimated and might be very common (at least) for generalist species in landscapes consisting of a mixture of agricultural and semi-natural habitats. These effects might also have—so far overlooked—implications for interspecific competition and mutualistic interactions in semi-natural habitats.}, language = {en} } @article{HendriksmaKuetingHaerteletal.2013, author = {Hendriksma, Harmen P. and K{\"u}ting, Meike and H{\"a}rtel, Stephan and N{\"a}ther, Astrid and Dohrmann, Anja B. and Steffan-Dewenter, Ingolf and Tebbe, Christoph C.}, title = {Effect of Stacked Insecticidal Cry Proteins from Maize Pollen on Nurse Bees (Apis mellifera carnica) and Their Gut Bacteria}, series = {PLoS ONE}, volume = {8}, journal = {PLoS ONE}, number = {3}, doi = {10.1371/journal.pone.0059589}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131025}, pages = {e59589}, year = {2013}, abstract = {Honey bee pollination is a key ecosystem service to nature and agriculture. However, biosafety research on genetically modified crops rarely considers effects on nurse bees from intact colonies, even though they receive and primarily process the largest amount of pollen. The objective of this study was to analyze the response of nurse bees and their gut bacteria to pollen from Bt maize expressing three different insecticidal Cry proteins (Cry1A.105, Cry2Ab2, and Cry3Bb1). Naturally Cry proteins are produced by bacteria (Bacillus thuringiensis). Colonies of Apis mellifera carnica were kept during anthesis in flight cages on field plots with the Bt maize, two different conventionally bred maize varieties, and without cages, 1-km outside of the experimental maize field to allow ad libitum foraging to mixed pollen sources. During their 10-days life span, the consumption of Bt maize pollen had no effect on their survival rate, body weight and rates of pollen digestion compared to the conventional maize varieties. As indicated by ELISA-quantification of Cry1A.105 and Cry3Bb1, more than 98\% of the recombinant proteins were degraded. Bacterial population sizes in the gut were not affected by the genetic modification. Bt-maize, conventional varieties and mixed pollen sources selected for significantly different bacterial communities which were, however, composed of the same dominant members, including Proteobacteria in the midgut and Lactobacillus sp. and Bifidobacterium sp. in the hindgut. Surprisingly, Cry proteins from natural sources, most likely B. thuringiensis, were detected in bees with no exposure to Bt maize. The natural occurrence of Cry proteins and the lack of detectable effects on nurse bees and their gut bacteria give no indication for harmful effects of this Bt maize on nurse honey bees.}, language = {en} } @article{BartomeusPottsSteffanDewenteretal.2014, author = {Bartomeus, Ignasi and Potts, Simon G. and Steffan-Dewenter, Ingolf and Vaissiere, Bernard E. and Woyciechowski, Michal and Krewenka, Kristin M. and Tscheulin, Thomas and Roberts, Stuart P. M. and Szentgyoergyi, Hajnalka and Westphal, Catrin and Bommarco, Riccardo}, title = {Contribution of insect pollinators to crop yield and quality varies with agricultural intensification}, series = {PEERJ}, volume = {2}, journal = {PEERJ}, number = {e328}, issn = {2167-9843}, doi = {10.7717/peerj.328}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116928}, year = {2014}, abstract = {Background. Up to 75\% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production. Methods. We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe. For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes. Results. Insect pollination enhanced average crop yield between 18 and 71\% depending on the crop. Yield quality was also enhanced in most crops. For instance, oilseed rape had higher oil and lower chlorophyll contents when adequately pollinated, the proportion of empty seeds decreased in buckwheat, and strawberries' commercial grade improved; however, we did not find higher nitrogen content in open pollinated field beans. Complex landscapes had a higher overall species richness of wild pollinators across crops, but visitation rates were only higher in complex landscapes for some crops. On the contrary, the overall yield was consistently enhanced by higher visitation rates, but not by higher pollinator richness. Discussion. For the four crops in this study, there is clear benefit delivered by pollinators on yield quantity and/or quality, but it is not maximized under current agricultural intensification. Honeybees, the most abundant pollinator, might partially compensate the loss of wild pollinators in some areas, but our results suggest the need of landscape-scale actions to enhance wild pollinator populations.}, language = {en} } @article{BreezeVaissiereBommarcoetal.2014, author = {Breeze, Tom D. and Vaissiere, Bernhard E. and Bommarco, Riccardo and Petanidou, Theodora and Seraphides, Nicos and Kozak, Lajos and Scheper, Jeroen and Biesmeijer, Jacobus C. and Kleijn, David and Gyldenk{\ae}rne, Steen and Moretti, Marco and Holzschuh, Andrea and Steffan-Dewenter, Ingolf and Stout, Jane C. and P{\"a}rtel, Meelis and Zobel, Martin and Potts, Simon G.}, title = {Agricultural Policies Exacerbate Honeybee Pollination Service Supply-Demand Mismatches Across Europe}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {1}, issn = {1932-6203}, doi = {10.1371/journal.pone.0082996}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117692}, pages = {e82996}, year = {2014}, abstract = {Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90\% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.}, language = {en} } @article{HopfenmuellerSteffanDewenterHolzschuh2014, author = {Hopfenmueller, Sebastian and Steffan-Dewenter, Ingolf and Holzschuh, Andrea}, title = {Trait-Specific Responses of Wild Bee Communities to Landscape Composition, Configuration and Local Factors}, doi = {10.1371/journal.pone.0104439}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112872}, year = {2014}, abstract = {Land-use intensification and loss of semi-natural habitats have induced a severe decline of bee diversity in agricultural landscapes. Semi-natural habitats like calcareous grasslands are among the most important bee habitats in central Europe, but they are threatened by decreasing habitat area and quality, and by homogenization of the surrounding landscape affecting both landscape composition and configuration. In this study we tested the importance of habitat area, quality and connectivity as well as landscape composition and configuration on wild bees in calcareous grasslands. We made detailed trait-specific analyses as bees with different traits might differ in their response to the tested factors. Species richness and abundance of wild bees were surveyed on 23 calcareous grassland patches in Southern Germany with independent gradients in local and landscape factors. Total wild bee richness was positively affected by complex landscape configuration, large habitat area and high habitat quality (i.e. steep slopes). Cuckoo bee richness was positively affected by complex landscape configuration and large habitat area whereas habitat specialists were only affected by the local factors habitat area and habitat quality. Small social generalists were positively influenced by habitat area whereas large social generalists (bumblebees) were positively affected by landscape composition (high percentage of semi-natural habitats). Our results emphasize a strong dependence of habitat specialists on local habitat characteristics, whereas cuckoo bees and bumblebees are more likely affected by the surrounding landscape. We conclude that a combination of large high-quality patches and heterogeneous landscapes maintains high bee species richness and communities with diverse trait composition. Such diverse communities might stabilize pollination services provided to crops and wild plants on local and landscape scales.}, language = {en} } @article{LeingaertnerHoissKraussetal.2014, author = {Leing{\"a}rtner, Annette and Hoiss, Bernhard and Krauss, Jochen and Steffan-Dewenter, Ingolf}, title = {Combined Effects of Extreme Climatic Events and Elevation on Nutritional Quality and Herbivory of Alpine Plants}, doi = {10.1371/journal.pone.0093881}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112812}, year = {2014}, abstract = {Climatic extreme events can cause the shift or disruption of plant-insect interactions due to altered plant quality, e.g. leaf carbon to nitrogen ratios, and phenology. However, the response of plant-herbivore interactions to extreme events and climatic gradients has been rarely studied, although climatic extremes will increase in frequency and intensity in the future and insect herbivores represent a highly diverse and functionally important group. We set up a replicated climate change experiment along elevational gradients in the German Alps to study the responses of three plant guilds and their herbivory by insects to extreme events (extreme drought, advanced and delayed snowmelt) versus control plots under different climatic conditions on 15 grassland sites. Our results indicate that elevational shifts in CN (carbon to nitrogen) ratios and herbivory depend on plant guild and season. CN ratios increased with altitude for grasses, but decreased for legumes and other forbs. In contrast to our hypotheses, extreme climatic events did not significantly affect CN ratios and herbivory. Thus, our study indicates that nutritional quality of plants and antagonistic interactions with insect herbivores are robust against seasonal climatic extremes. Across the three functional plant guilds, herbivory increased with nitrogen concentrations. Further, increased CN ratios indicate a reduction in nutritional plant quality with advancing season. Although our results revealed no direct effects of extreme climatic events, the opposing responses of plant guilds along elevation imply that competitive interactions within plant communities might change under future climates, with unknown consequences for plant-herbivore interactions and plant community composition.}, language = {en} } @article{KellerGrimmerSteffanDewenter2013, author = {Keller, Alexander and Grimmer, Gudrun and Steffan-Dewenter, Ingolf}, title = {Diverse Microbiota Identified in Whole Intact Nest Chambers of the Red Mason Bee Osmia bicornis (Linnaeus 1758)}, series = {PLoS One}, journal = {PLoS One}, doi = {10.1371/journal.pone.0078296}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97305}, year = {2013}, abstract = {Microbial activity is known to have profound impact on bee ecology and physiology, both by beneficial and pathogenic effects. Most information about such associations is available for colony-building organisms, and especially the honey bee. There, active manipulations through worker bees result in a restricted diversity of microbes present within the colony environment. Microbial diversity in solitary bee nests remains unstudied, although their larvae face a very different situation compared with social bees by growing up in isolated compartments. Here, we assessed the microbiota present in nests and pre-adults of Osmia bicornis, the red mason bee, by culture-independent pyrosequencing. We found high bacterial diversity not comparable with honey bee colonies. We identified a variety of bacteria potentially with positive or negative interactions for bee larvae. However, most of the other diverse bacteria present in the nests seem to originate from environmental sources through incorporated nest building material and stored pollen. This diversity of microorganisms may cause severe larval mortality and require specific physiological or symbiotic adaptations against microbial threats. They may however also profit from such a diverse environment through gain of mutualistic partners. We conclude that further studies of microbiota interaction in solitary bees will improve the understanding of fitness components and populations dynamics.}, language = {en} } @article{LaswayPetersNjovuetal.2022, author = {Lasway, Julius V. and Peters, Marcell K. and Njovu, Henry K. and Eardley, Connal and Pauly, Alain and Steffan-Dewenter, Ingolf}, title = {Agricultural intensification with seasonal fallow land promotes high bee diversity in Afrotropical drylands}, series = {Journal of Applied Ecology}, volume = {59}, journal = {Journal of Applied Ecology}, number = {12}, doi = {10.1111/1365-2664.14296}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311877}, pages = {3014 -- 3026}, year = {2022}, abstract = {The exponential increase in the human population in tandem with increased food demand has caused agriculture to be the global-dominant form of land use. Afrotropical drylands are currently facing the loss of natural savannah habitats and agricultural intensification with largely unknown consequences for bees. Here we investigate the effects of agricultural intensification on bee assemblages in the Afrotropical drylands of northern Tanzania. We disentangled the direct effects of agricultural intensification and temperature on bee richness from indirect effects mediated by changes in floral resources. We collected data from 24 study sites representing three levels of management intensity (natural savannah, moderate intensive and highly intensive agriculture) spanning an extensive gradient of mean annual temperature (MAT) in northern Tanzania. We used ordinary linear models and path analysis to test the effects of agricultural intensity and MAT on bee species richness, bee species composition and body-size variation of bee communities. We found that bee species richness increased with agricultural intensity and with increasing temperature. The effects of agricultural intensity and temperature on bee species richness were mediated by the positive effects of agriculture and temperature on the richness of floral resources used by bees. During the off-growing season, agricultural land was characterized by an extensive period of fallow land holding a very high density of flowering plants with unique bee species composition. The increase in bee diversity in agricultural habitats paralleled an increasing variation of bee body sizes with agricultural intensification that, however, diminished in environments with higher temperatures. Synthesis and applications. Our study reveals that bee assemblages in Afrotropical drylands benefit from agricultural intensification in the way it is currently practiced. However, further land-use intensification, including year-round irrigated crop monocultures and excessive use of agrochemicals, is likely to exert a negative impact on bee diversity and pollination services, as reported in temperate regions. Moreover, several bee species were restricted to natural savannah habitats. To conserve bee communities and guarantee pollination services in the region, a mixture of savannah and agriculture, with long periods of fallow land should be maintained.}, language = {en} } @article{SponslerRequierKallniketal.2022, author = {Sponsler, Douglas B. and Requier, Fabrice and Kallnik, Katharina and Classen, Alice and Maihoff, Fabienne and Sieger, Johanna and Steffan-Dewenter, Ingolf}, title = {Contrasting patterns of richness, abundance, and turnover in mountain bumble bees and their floral hosts}, series = {Ecology}, volume = {103}, journal = {Ecology}, number = {7}, doi = {10.1002/ecy.3712}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287199}, year = {2022}, abstract = {Environmental gradients generate and maintain biodiversity on Earth. Mountain slopes are among the most pronounced terrestrial environmental gradients, and the elevational structure of species and their interactions can provide unique insight into the processes that govern community assembly and function in mountain ecosystems. We recorded bumble bee-flower interactions over 3 years along a 1400-m elevational gradient in the German Alps. Using nonlinear modeling techniques, we analyzed elevational patterns at the levels of abundance, species richness, species β-diversity, and interaction β-diversity. Though floral richness exhibited a midelevation peak, bumble bee richness increased with elevation before leveling off at the highest sites, demonstrating the exceptional adaptation of these bees to cold temperatures and short growing seasons. In terms of abundance, though, bumble bees exhibited divergent species-level responses to elevation, with a clear separation between species preferring low versus high elevations. Overall interaction β-diversity was mainly caused by strong turnover in the floral community, which exhibited a well-defined threshold of β-diversity rate at the tree line ecotone. Interaction β-diversity increased sharply at the upper extreme of the elevation gradient (1800-2000 m), an interval over which we also saw steep decline in floral richness and abundance. Turnover of bumble bees along the elevation gradient was modest, with the highest rate of β-diversity occurring over the interval from low- to mid-elevation sites. The contrast between the relative robustness bumble bee communities and sensitivity of plant communities to the elevational gradient in our study suggests that the strongest effects of climate change on mountain bumble bees may be indirect effects mediated by the responses of their floral hosts, though bumble bee species that specialize in high-elevation habitats may also experience significant direct effects of warming.}, language = {en} } @article{GebertSteffan‐DewenterKronbachetal.2022, author = {Gebert, Friederike and Steffan-Dewenter, Ingolf and Kronbach, Patrick and Peters, Marcell K.}, title = {The role of diversity, body size and climate in dung removal: A correlative and experimental approach}, series = {Journal of Animal Ecology}, volume = {91}, journal = {Journal of Animal Ecology}, number = {11}, doi = {10.1111/1365-2656.13798}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293907}, pages = {2181 -- 2191}, year = {2022}, abstract = {The mechanisms by which climatic changes influence ecosystem functions, that is, by a direct climatic control of ecosystem processes or by modifying richness and trait compositions of species communities, remain unresolved. This study is a contribution to this discourse by elucidating the linkages between climate, land use, biodiversity, body size and ecosystem functions. We disentangled direct climatic from biodiversity-mediated effects by using dung removal by dung beetles as a model system and by combining correlative field data and exclosure experiments along an extensive elevational gradient on Mt. Kilimanjaro, Tanzania. Dung removal declined with increasing elevation, being associated with a strong reduction in the richness and body size traits of dung beetle communities. Climate influenced dung removal rates by modifying biodiversity rather than by direct effects. The biodiversity-ecosystem effect was driven by a change in the mean body size of dung beetles. Dung removal rates were strongly reduced when large dung beetles were experimentally excluded. This study underscores that climate influences ecosystem functions mainly by modifying biodiversity and underpins the important role of body size for dung removal.}, language = {en} } @article{FrickeRedlichZhangetal.2023, author = {Fricke, Ute and Redlich, Sarah and Zhang, Jie and Benjamin, Caryl S. and Englmeier, Jana and Ganuza, Cristina and Haensel, Maria and Riebl, Rebekka and Rojas-Botero, Sandra and Tobisch, Cynthia and Uhler, Johannes and Uphus, Lars and Steffan-Dewenter, Ingolf}, title = {Earlier flowering of winter oilseed rape compensates for higher pest pressure in warmer climates}, series = {Journal of Applied Ecology}, volume = {60}, journal = {Journal of Applied Ecology}, number = {2}, doi = {10.1111/1365-2664.14335}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312562}, pages = {365 -- 375}, year = {2023}, abstract = {Global warming can increase insect pest pressure by enhancing reproductive rates. Whether this translates into yield losses depends on phenological synchronisation of pests with their host plants and natural enemies. Simultaneously, landscape composition may mitigate climate effects by shaping the resource availability for pests and their antagonists. Here, we study the combined effects of temperature and landscape composition on pest abundances, larval parasitism, crop damage and yield, while also considering crop phenology, to identify strategies for sustainable management of oilseed rape (OSR) pests under warming climates. In all, 29 winter OSR crop fields were investigated in different climates (defined by multi-annual mean temperature, MAT) and landscape contexts in Bavaria, Germany. We measured abundances of adult pollen beetles and stem weevil larvae, pollen beetle larval parasitism, bud loss, stem damage and seed yield, and calculated the flowering date from growth stage observations. Landscape parameters (proportion of non-crop and OSR area, change in OSR area relative to the previous year) were calculated at six spatial scales (0.6-5 km). Pollen beetle abundance increased with MAT but to different degrees depending on the landscape context, that is, increased less strongly when OSR proportions were high (1-km scale), interannually constant (5-km scale) or both. In contrast, stem weevil abundance and stem damage did not respond to landscape composition nor MAT. Pollen beetle larval parasitism was overall low, but occasionally exceeded 30\% under both low and high MAT and with reduced OSR area (0.6-km scale). Despite high pollen beetle abundance in warm climates, yields were high when OSR flowered early. Thereby, higher temperatures favoured early flowering. Only among late-flowering OSR crop fields yield was higher in cooler than warmer climates. Bud loss responded analogously. Landscape composition did not substantially affect bud loss and yield. Synthesis and applications: Earlier flowering of winter OSR compensates for higher pollen beetle abundance in warmer climates, while interannual continuity of OSR area prevents high pollen beetle abundance in the first place. Thus, regional coordination of crop rotation and crop management promoting early flowering may contribute to sustainable pest management in OSR under current and future climatic conditions.}, language = {en} } @article{KohlSteffan‐Dewenter2022, author = {Kohl, Patrick L. and Steffan-Dewenter, Ingolf}, title = {Nectar robbing rather than pollinator availability constrains reproduction of a bee-flowered plant at high elevations}, series = {Ecosphere}, volume = {13}, journal = {Ecosphere}, number = {6}, doi = {10.1002/ecs2.4077}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287141}, year = {2022}, abstract = {Abiotic factors are generally assumed to determine whether species can exist at the extreme ends of environmental gradients, for example, at high elevations, whereas the role of biotic interactions is less clear. On temperate mountains, insect-pollinated plant species with bilaterally symmetrical flowers exhibit a parallel elevational decline in species richness and abundance with bees. This suggests that the lack of mutualistic interaction partners sets the elevational range limits of plants via a reduction in reproductive success. We used the bee-pollinated mountain plant Clinopodium alpinum (Lamiaceae), which blooms along a continuous 1000-m elevational gradient and has bilaterally symmetrical flowers, as a model to test the predicted parallel elevational decline in flower visitation and seed production. Although the community of flower visitors changed with elevation, the flower visitation rate by the most frequent visitors, bumble bees (33.8\% of legitimate visits), and the overall rate of flower visitation by potential pollinators did not vary significantly with elevation. However, we discovered that nectar robbing by bumble bees and nectar theft by ants, two interactions with potentially negative effects on flowers, sharply increased with elevation. Seed set depended on pollinators across elevations and followed a weak hump-shaped pattern, peaking at mid-elevations and decreasing by about 20\% toward both elevational range edges. Considering the mid- and high elevations, elevational variation in seed production could not be explained by legitimate bee visitation rates but was inversely correlated with the frequency of nectar robbing. Our observations challenge the hypothesis that a decrease in the availability of pollinators limits seed production of bee-flowered plants at high elevations but suggest that an increase in negative interactions (nectar robbing and larceny) constrains reproductive success.}, language = {en} } @article{SchilcherHilsmannAnkenbrandetal.2022, author = {Schilcher, Felix and Hilsmann, Lioba and Ankenbrand, Markus J. and Krischke, Markus and Mueller, Martin J. and Steffan-Dewenter, Ingolf and Scheiner, Ricarda}, title = {Honeybees are buffered against undernourishment during larval stages}, series = {Frontiers in Insect Science}, volume = {2}, journal = {Frontiers in Insect Science}, issn = {2673-8600}, doi = {10.3389/finsc.2022.951317}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304646}, year = {2022}, abstract = {The negative impact of juvenile undernourishment on adult behavior has been well reported for vertebrates, but relatively little is known about invertebrates. In honeybees, nutrition has long been known to affect task performance and timing of behavioral transitions. Whether and how a dietary restriction during larval development affects the task performance of adult honeybees is largely unknown. We raised honeybees in-vitro, varying the amount of a standardized diet (150 µl, 160 µl, 180 µl in total). Emerging adults were marked and inserted into established colonies. Behavioral performance of nurse bees and foragers was investigated and physiological factors known to be involved in the regulation of social organization were quantified. Surprisingly, adult honeybees raised under different feeding regimes did not differ in any of the behaviors observed. No differences were observed in physiological parameters apart from weight. Honeybees were lighter when undernourished (150 µl), while they were heavier under the overfed treatment (180 µl) compared to the control group raised under a normal diet (160 µl). These data suggest that dietary restrictions during larval development do not affect task performance or physiology in this social insect despite producing clear effects on adult weight. We speculate that possible effects of larval undernourishment might be compensated during the early period of adult life.}, language = {en} } @article{Voulgari‐KokotaAnkenbrandGrimmeretal.2019, author = {Voulgari-Kokota, Anna and Ankenbrand, Markus J. and Grimmer, Gudrun and Steffan-Dewenter, Ingolf and Keller, Alexander}, title = {Linking pollen foraging of megachilid bees to their nest bacterial microbiota}, series = {Ecology and Evolution}, volume = {2019}, journal = {Ecology and Evolution}, number = {9}, issn = {00}, doi = {10.1002/ece3.5599}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201749}, pages = {10788-10800}, year = {2019}, abstract = {Solitary bees build their nests by modifying the interior of natural cavities, and they provision them with food by importing collected pollen. As a result, the microbiota of the solitary bee nests may be highly dependent on introduced materials. In order to investigate how the collected pollen is associated with the nest microbiota, we used metabarcoding of the ITS2 rDNA and the 16S rDNA to simultaneously characterize the pollen composition and the bacterial communities of 100 solitary bee nest chambers belonging to seven megachilid species. We found a weak correlation between bacterial and pollen alpha diversity and significant associations between the composition of pollen and that of the nest microbiota, contributing to the understanding of the link between foraging and bacteria acquisition for solitary bees. Since solitary bees cannot establish bacterial transmission routes through eusociality, this link could be essential for obtaining bacterial symbionts for this group of valuable pollinators.}, language = {en} } @article{SchilcherHilsmannRauscheretal.2021, author = {Schilcher, Felix and Hilsmann, Lioba and Rauscher, Lisa and Değirmenci, Laura and Krischke, Markus and Krischke, Beate and Ankenbrand, Markus and Rutschmann, Benjamin and Mueller, Martin J. and Steffan-Dewenter, Ingolf and Scheiner, Ricarda}, title = {In vitro rearing changes social task performance and physiology in honeybees}, series = {Insects}, volume = {13}, journal = {Insects}, number = {1}, issn = {2075-4450}, doi = {10.3390/insects13010004}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252305}, year = {2021}, abstract = {In vitro rearing of honeybee larvae is an established method that enables exact control and monitoring of developmental factors and allows controlled application of pesticides or pathogens. However, only a few studies have investigated how the rearing method itself affects the behavior of the resulting adult honeybees. We raised honeybees in vitro according to a standardized protocol: marking the emerging honeybees individually and inserting them into established colonies. Subsequently, we investigated the behavioral performance of nurse bees and foragers and quantified the physiological factors underlying the social organization. Adult honeybees raised in vitro differed from naturally reared honeybees in their probability of performing social tasks. Further, in vitro-reared bees foraged for a shorter duration in their life and performed fewer foraging trips. Nursing behavior appeared to be unaffected by rearing condition. Weight was also unaffected by rearing condition. Interestingly, juvenile hormone titers, which normally increase strongly around the time when a honeybee becomes a forager, were significantly lower in three- and four-week-old in vitro bees. The effects of the rearing environment on individual sucrose responsiveness and lipid levels were rather minor. These data suggest that larval rearing conditions can affect the task performance and physiology of adult bees despite equal weight, pointing to an important role of the colony environment for these factors. Our observations of behavior and metabolic pathways offer important novel insight into how the rearing environment affects adult honeybees.}, language = {en} } @techreport{MuellerSchererLorenzenAmmeretal.2022, author = {M{\"u}ller, J{\"o}rg and Scherer-Lorenzen, Michael and Ammer, Christian and Eisenhauer, Nico and Seidel, Dominik and Schuldt, Bernhard and Biedermann, Peter and Schmitt, Thomas and K{\"u}nzer, Claudia and Wegmann, Martin and Cesarz, Simone and Peters, Marcell and Feldhaar, Heike and Steffan-Dewenter, Ingolf and Claßen, Alice and B{\"a}ssler, Claus and von Oheimb, Goddert and Fichtner, Andreas and Thorn, Simon and Weisser, Wolfgang}, title = {BETA-FOR: Erh{\"o}hung der strukturellen Diversit{\"a}t zwischen Waldbest{\"a}nden zur Erh{\"o}hung der Multidiversit{\"a}t und Multifunktionalit{\"a}t in Produktionsw{\"a}ldern. Antragstext f{\"u}r die DFG Forschungsgruppe FOR 5375}, doi = {10.25972/OPUS-29084}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290849}, pages = {210}, year = {2022}, abstract = {Der in j{\"u}ngster Zeit beobachtete kontinuierliche Verlust der β-Diversit{\"a}t in {\"O}kosystemen deutet auf homogene Gemeinschaften auf Landschaftsebene hin, was haupts{\"a}chlich auf die steigende Landnutzungsintensit{\"a}t zur{\"u}ckgef{\"u}hrt wird. Biologische Vielfalt ist mit zahlreichen Funktionen und der Stabilit{\"a}t von {\"O}kosystemen verkn{\"u}pft. Es ist daher zu erwarten, dass eine abnehmende β-Diversit{\"a}t auch die Multifunktionalit{\"a}t verringert. Wir kombinieren hier Fachwissen aus der Forstwissenschaft, der {\"O}kologie, der Fernerkundung, der chemischen {\"O}kologie und der Statistik in einem gemeinschaftlichen und experimentellen β-Diversit{\"a}tsdesign, um einerseits die Auswirkungen der Homogenisierung zu bewerten und andererseits Konzepte zu entwickeln, um negative Auswirkungen durch Homogenisierung in W{\"a}ldern r{\"u}ckg{\"a}ngig zu machen. Konkret werden wir uns mit der Frage besch{\"a}ftigen, ob die Verbesserung der strukturellen β-Komplexit{\"a}t (ESBC) in W{\"a}ldern durch Waldbau oder nat{\"u}rliche St{\"o}rungen die Biodiversit{\"a}t und Multifunktionalit{\"a}t in ehemals homogenen Produktionsw{\"a}ldern erh{\"o}hen kann. Unser Ansatz wird m{\"o}gliche Mechanismen hinter den beobachteten Homogenisierungs-Diversit{\"a}ts-Beziehungen identifizieren und zeigen, wie sich diese auf die Multifunktionalit{\"a}t auswirken. An elf Standorten in ganz Deutschland haben wir dazu zwei Waldbest{\"a}nde als zwei kleine "Waldlandschaften" ausgew{\"a}hlt. In einem dieser beiden Best{\"a}nde haben wir ESBC (Enhancement of Structural Beta Complexity)-Behandlungen durchgef{\"u}hrt. Im zweiten, dem Kontrollbestand, werden wir die gleich Anzahl 50x50m Parzellen ohne ESBC einrichten. Auf allen Parzellen werden wir 18 taxonomische Artengruppen aller trophischer Ebenen und 21 {\"O}kosystemfunktionen, einschließlich der wichtigsten Funktionen in W{\"a}ldern der gem{\"a}ßigten Zonen, messen. Der statistische Rahmen wird eine umfassende Analyse der Biodiversit{\"a}t erm{\"o}glichen, indem verschiedenen Aspekte (taxonomische, funktionelle und phylogenetische Vielfalt) auf verschiedenen Skalenebenen (α-, β-, γ-Diversit{\"a}t) quantifiziert werden. Um die Gesamtdiversit{\"a}t zu kombinieren, werden wir das Konzept der Multidiversit{\"a}t auf die 18 Taxa anwenden. Wir werden neue Ans{\"a}tze zur Quantifizierung und Aufteilung der Multifunktionalit{\"a}t auf α- und β-Skalen verwenden und entwickeln. Durch die experimentelle Beschreibung des Zusammenhangs zwischen β-Diversit{\"a}t und Multifunktionalit{\"a}t in einer Reallandschaft wird unsere Forschung einen neuen Weg einschlagen. Dar{\"u}ber hinaus werden wir dazu beitragen, verbesserte Leitlinien f{\"u}r waldbauliche Konzepte und f{\"u}r das Management nat{\"u}rlicher St{\"o}rungen zu entwickeln, um Homogenisierungseffekte der Vergangenheit umzukehren.}, subject = {Wald{\"o}kosystem}, language = {en} } @article{MartinReinekingSeoetal.2015, author = {Martin, Emily A. and Reineking, Bj{\"o}rn and Seo, Bumsuk and Steffan-Dewenter, Ingolf}, title = {Pest control of aphids depends on landscape complexity and natural enemy interactions}, series = {PeerJ}, volume = {3}, journal = {PeerJ}, number = {e1095}, doi = {10.7717/peerj.1095}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148393}, year = {2015}, abstract = {Aphids are a major concern in agricultural crops worldwide, and control by natural enemies is an essential component of the ecological intensification of agriculture. Although the complexity of agricultural landscapes is known to influence natural enemies of pests, few studies have measured the degree of pest control by different enemy guilds across gradients in landscape complexity. Here, we use multiple natural-enemy exclosures replicated in 18 fields across a gradient in landscape complexity to investigate (1) the strength of natural pest control across landscapes, measured as the difference between pest pressure in the presence and in the absence of natural enemies; (2) the differential contributions of natural enemy guilds to pest control, and the nature of their interactions across landscapes. We show that natural pest control of aphids increased up to six-fold from simple to complex landscapes. In the absence of pest control, aphid population growth was higher in complex than simple landscapes, but was reduced by natural enemies to similar growth rates across all landscapes. The effects of enemy guilds were landscape-dependent. Particularly in complex landscapes, total pest control was supplied by the combined contribution of flying insects and ground-dwellers. Birds had little overall impact on aphid control. Despite evidence for intraguild predation of flying insects by ground-dwellers and birds, the overall effect of enemy guilds on aphid control was complementary. Understanding pest control services at large spatial scales is critical to increase the success of ecological intensification schemes. Our results suggest that, where aphids are the main pest of concern, interactions between natural enemies are largely complementary and lead to a strongly positive effect of landscape complexity on pest control. Increasing the availability of seminatural habitats in agricultural landscapes may thus benefit not only natural enemies, but also the effectiveness of aphid natural pest control.}, language = {en} } @article{PetersHempAppelhansetal.2016, author = {Peters, Marcell K. and Hemp, Andreas and Appelhans, Tim and Behler, Christina and Classen, Alice and Detsch, Florian and Ensslin, Andreas and Ferger, Stefan W. and Frederiksen, Sara B. and Gebert, Frederike and Haas, Michael and Helbig-Bonitz, Maria and Hemp, Claudia and Kindeketa, William J. and Mwangomo, Ephraim and Ngereza, Christine and Otte, Insa and R{\"o}der, Juliane and Rutten, Gemma and Costa, David Schellenberger and Tardanico, Joseph and Zancolli, Giulia and Deckert, J{\"u}rgen and Eardley, Connal D. and Peters, Ralph S. and R{\"o}del, Mark-Oliver and Schleuning, Matthias and Ssymank, Axel and Kakengi, Victor and Zhang, Jie and B{\"o}hning-Gaese, Katrin and Brandl, Roland and Kalko, Elisabeth K.V. and Kleyer, Michael and Nauss, Thomas and Tschapka, Marco and Fischer, Markus and Steffan-Dewenter, Ingolf}, title = {Predictors of elevational biodiversity gradients change from single taxa to the multi-taxa community level}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms13736}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169374}, year = {2016}, abstract = {The factors determining gradients of biodiversity are a fundamental yet unresolved topic in ecology. While diversity gradients have been analysed for numerous single taxa, progress towards general explanatory models has been hampered by limitations in the phylogenetic coverage of past studies. By parallel sampling of 25 major plant and animal taxa along a 3.7 km elevational gradient on Mt. Kilimanjaro, we quantify cross-taxon consensus in diversity gradients and evaluate predictors of diversity from single taxa to a multi-taxa community level. While single taxa show complex distribution patterns and respond to different environmental factors, scaling up diversity to the community level leads to an unambiguous support for temperature as the main predictor of species richness in both plants and animals. Our findings illuminate the influence of taxonomic coverage for models of diversity gradients and point to the importance of temperature for diversification and species coexistence in plant and animal communities.}, language = {en} } @article{HornickRichterHarpoleetal.2022, author = {Hornick, Thomas and Richter, Anett and Harpole, William Stanley and Bastl, Maximilian and Bohlmann, Stephanie and Bonn, Aletta and Bumberger, Jan and Dietrich, Peter and Gemeinholzer, Birgit and Grote, R{\"u}diger and Heinold, Bernd and Keller, Alexander and Luttkus, Marie L. and M{\"a}der, Patrick and Motivans Švara, Elena and Passonneau, Sarah and Punyasena, Surangi W. and Rakosy, Demetra and Richter, Ronny and Sickel, Wiebke and Steffan-Dewenter, Ingolf and Theodorou, Panagiotis and Treudler, Regina and Werchan, Barbora and Werchan, Matthias and Wolke, Ralf and Dunker, Susanne}, title = {An integrative environmental pollen diversity assessment and its importance for the Sustainable Development Goals}, series = {Plants, People, Planet}, volume = {4}, journal = {Plants, People, Planet}, number = {2}, doi = {10.1002/ppp3.10234}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276487}, pages = {110 -- 121}, year = {2022}, abstract = {Societal Impact Statement Pollen relates to many aspects of human and environmental health, which protection and improvement are endorsed by the United Nations Sustainable Development Goals. By highlighting these connections in the frame of current challenges in monitoring and research, we discuss the need of more integrative and multidisciplinary pollen research related to societal needs, improving health of humans and our ecosystems for a sustainable future. Summary Pollen is at once intimately part of the reproductive cycle of seed plants and simultaneously highly relevant for the environment (pollinators, vector for nutrients, or organisms), people (food safety and health), and climate (cloud condensation nuclei and climate reconstruction). We provide an interdisciplinary perspective on the many and connected roles of pollen to foster a better integration of the currently disparate fields of pollen research, which would benefit from the sharing of general knowledge, technical advancements, or data processing solutions. We propose a more interdisciplinary and holistic research approach that encompasses total environmental pollen diversity (ePD) (wind and animal and occasionally water distributed pollen) at multiple levels of diversity (genotypic, phenotypic, physiological, chemical, and functional) across space and time. This interdisciplinary approach holds the potential to contribute to pressing human issues, including addressing United Nations Sustainable Development Goals, fostering social and political awareness of these tiny yet important and fascinating particles.}, language = {en} } @article{DePalmaAbrahamczykAizenetal.2016, author = {De Palma, Adriana and Abrahamczyk, Stefan and Aizen, Marcelo A. and Albrecht, Matthias and Basset, Yves and Bates, Adam and Blake, Robin J. and Boutin, C{\´e}line and Bugter, Rob and Connop, Stuart and Cruz-L{\´o}pez, Leopoldo and Cunningham, Saul A. and Darvill, Ben and Diek{\"o}tter, Tim and Dorn, Silvia and Downing, Nicola and Entling, Martin H. and Farwig, Nina and Felicioli, Antonio and Fonte, Steven J. and Fowler, Robert and Franzen, Markus Franz{\´e}n and Goulson, Dave and Grass, Ingo and Hanley, Mick E. and Hendrix, Stephen D. and Herrmann, Farina and Herzog, Felix and Holzschuh, Andrea and Jauker, Birgit and Kessler, Michael and Knight, M. E. and Kruess, Andreas and Lavelle, Patrick and Le F{\´e}on, Violette and Lentini, Pia and Malone, Louise A. and Marshall, Jon and Mart{\´i}nez Pach{\´o}n, Eliana and McFrederick, Quinn S. and Morales, Carolina L. and Mudri-Stojnic, Sonja and Nates-Parra, Guiomar and Nilsson, Sven G. and {\"O}ckinger, Erik and Osgathorpe, Lynne and Parra-H, Alejandro and Peres, Carlos A. and Persson, Anna S. and Petanidou, Theodora and Poveda, Katja and Power, Eileen F. and Quaranta, Marino and Quintero, Carolina and Rader, Romina and Richards, Miriam H. and Roulston, T'ai and Rousseau, Laurent and Sadler, Jonathan P. and Samneg{\aa}rd, Ulrika and Schellhorn, Nancy A. and Sch{\"u}epp, Christof and Schweiger, Oliver and Smith-Pardo, Allan H. and Steffan-Dewenter, Ingolf and Stout, Jane C. and Tonietto, Rebecca K. and Tscharntke, Teja and Tylianakis, Jason M. and Verboven, Hans A. F. and Vergara, Carlos H. and Verhulst, Jort and Westphal, Catrin and Yoon, Hyung Joo and Purvis, Andy}, title = {Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, doi = {10.1038/srep31153}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167642}, pages = {31153}, year = {2016}, abstract = {Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises.}, language = {en} } @article{KleijnWinfreeBartomeusetal.2015, author = {Kleijn, David and Winfree, Rachael and Bartomeus, Ignasi and Carvalheiro, Lu{\´i}sa G. and Henry, Mickael and Isaacs, Rufus and Klein, Alexandra-Maria and Kremen, Claire and M'Gonigle, Leithen K. and Rader, Romina and Ricketts, Taylor H. and Williams, Neal M. and Adamson, Nancy Lee and Ascher, John S. and B{\´a}ldi, Andr{\´a}s and Bat{\´a}ry, P{\´e}ter and Benjamin, Faye and Biesmeijer, Jacobus C. and Blitzer, Eleanor J. and Bommarco, Riccardo and Brand, Mariette R. and Bretagnolle, Vincent and Button, Lindsey and Cariveau, Daniel P. and Chifflet, R{\´e}my and Colville, Jonathan F. and Danforth, Bryan N. and Elle, Elizabeth and Garratt, Michael P. D. and Herzog, Felix and Holzschuh, Andrea and Howlett, Brad G. and Jauker, Frank and Jha, Shalene and Knop, Eva and Krewenka, Kristin M. and Le F{\´e}on, Violette and Mandelik, Yael and May, Emily A. and Park, Mia G. and Pisanty, Gideon and Reemer, Menno and Riedinger, Verena and Rollin, Orianne and Rundl{\"o}f, Maj and Sardi{\~n}as, Hillary S. and Scheper, Jeroen and Sciligo, Amber R. and Smith, Henrik G. and Steffan-Dewenter, Ingolf and Thorp, Robbin and Tscharntke, Teja and Verhulst, Jort and Viana, Blandina F. and Vaissi{\`e}re, Bernard E. and Veldtman, Ruan and Ward, Kimiora L. and Westphal, Catrin and Potts, Simon G.}, title = {Delivery of crop pollination services is an insufficient argument for wild pollinator conservation}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, number = {7414}, doi = {10.1038/ncomms8414}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151879}, year = {2015}, abstract = {There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost- effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost- effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.}, language = {en} } @article{HolzschuhDaineseGonzalezVaroetal.2016, author = {Holzschuh, Andrea and Dainese, Matteo and Gonzalez-Varo, Juan P. and Mudri-Stojnic, Sonja and Riedinger, Verena and Rundl{\"o}f, Maj and Scheper, Jeroen and Wickens, Jennifer B. and Wickens, Victoria J. and Bommarco, Riccardo and Kleijn, David and Potts, Simon G. and Roberts, Stuart P. M. and Smith, Henrik G. and Vil{\`a}, Montserrat and Vujic, Ante and Steffan-Dewenter, Ingolf}, title = {Mass-flowering crops dilute pollinator abundance in agricultural landscapes across Europe}, series = {Ecology Letters}, volume = {19}, journal = {Ecology Letters}, number = {10}, doi = {10.1111/ele.12657}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187356}, pages = {1228-1236}, year = {2016}, abstract = {Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator- dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes.}, language = {en} } @article{KohlRutschmannSteffanDewenter2022, author = {Kohl, Patrick L. and Rutschmann, Benjamin and Steffan-Dewenter, Ingolf}, title = {Population demography of feral honeybee colonies in central European forests}, series = {Royal Society Open Science}, volume = {9}, journal = {Royal Society Open Science}, number = {8}, issn = {2054-5703}, doi = {10.1098/rsos.220565}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301335}, year = {2022}, abstract = {European honeybee populations are considered to consist only of managed colonies, but recent censuses have revealed that wild/feral colonies still occur in various countries. To gauge the ecological and evolutionary relevance of wild-living honeybees, information is needed on their population demography. We monitored feral honeybee colonies in German forests for up to 4 years through regular inspections of woodpecker cavity trees and microsatellite genotyping. Each summer, about 10\% of the trees were occupied, corresponding to average densities of 0.23 feral colonies km\(^{-2}\) (an estimated 5\% of the regional honeybee populations). Populations decreased moderately until autumn but dropped massively during winter, so that their densities were only about 0.02 colonies km\(^{-2}\) in early spring. During the reproductive (swarming) season, in May and June, populations recovered, with new swarms preferring nest sites that had been occupied in the previous year. The annual survival rate and the estimated lifespan of feral colonies (n = 112) were 10.6\% and 0.6 years, respectively. We conclude that managed forests in Germany do not harbour self-sustaining feral honeybee populations, but they are recolonized every year by swarms escaping from apiaries.}, language = {en} } @article{EnglmeiervonHoermannRiekeretal.2022, author = {Englmeier, Jana and von Hoermann, Christian and Rieker, Daniel and Benbow, Marc Eric and Benjamin, Caryl and Fricke, Ute and Ganuza, Cristina and Haensel, Maria and Lackner, Tom{\´a}š and Mitesser, Oliver and Redlich, Sarah and Riebl, Rebekka and Rojas-Botero, Sandra and Rummler, Thomas and Salamon, J{\"o}rg-Alfred and Sommer, David and Steffan-Dewenter, Ingolf and Tobisch, Cynthia and Uhler, Johannes and Uphus, Lars and Zhang, Jie and M{\"u}ller, J{\"o}rg}, title = {Dung-visiting beetle diversity is mainly affected by land use, while community specialization is driven by climate}, series = {Ecology and Evolution}, volume = {12}, journal = {Ecology and Evolution}, number = {10}, issn = {2045-7758}, doi = {10.1002/ece3.9386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312846}, year = {2022}, abstract = {Dung beetles are important actors in the self-regulation of ecosystems by driving nutrient cycling, bioturbation, and pest suppression. Urbanization and the sprawl of agricultural areas, however, destroy natural habitats and may threaten dung beetle diversity. In addition, climate change may cause shifts in geographical distribution and community composition. We used a space-for-time approach to test the effects of land use and climate on α-diversity, local community specialization (H\(_2\)′) on dung resources, and γ-diversity of dung-visiting beetles. For this, we used pitfall traps baited with four different dung types at 115 study sites, distributed over a spatial extent of 300 km × 300 km and 1000 m in elevation. Study sites were established in four local land-use types: forests, grasslands, arable sites, and settlements, embedded in near-natural, agricultural, or urban landscapes. Our results show that abundance and species density of dung-visiting beetles were negatively affected by agricultural land use at both spatial scales, whereas γ-diversity at the local scale was negatively affected by settlements and on a landscape scale equally by agricultural and urban land use. Increasing precipitation diminished dung-visiting beetle abundance, and higher temperatures reduced community specialization on dung types and γ-diversity. These results indicate that intensive land use and high temperatures may cause a loss in dung-visiting beetle diversity and alter community networks. A decrease in dung-visiting beetle diversity may disturb decomposition processes at both local and landscape scales and alter ecosystem functioning, which may lead to drastic ecological and economic damage.}, language = {en} } @article{GanuzaRedlichUhleretal.2022, author = {Ganuza, Cristina and Redlich, Sarah and Uhler, Johannes and Tobisch, Cynthia and Rojas-Botero, Sandra and Peters, Marcell K. and Zhang, Jie and Benjamin, Caryl S. and Englmeier, Jana and Ewald, J{\"o}rg and Fricke, Ute and Haensel, Maria and Kollmann, Johannes and Riebl, Rebekka and Uphus, Lars and M{\"u}ller, J{\"o}rg and Steffan-Dewenter, Ingolf}, title = {Interactive effects of climate and land use on pollinator diversity differ among taxa and scales}, series = {Science Advances}, volume = {8}, journal = {Science Advances}, number = {18}, doi = {10.1126/sciadv.abm9359}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301303}, year = {2022}, abstract = {Changes in climate and land use are major threats to pollinating insects, an essential functional group. Here, we unravel the largely unknown interactive effects of both threats on seven pollinator taxa using a multiscale space-for-time approach across large climate and land-use gradients in a temperate region. Pollinator community composition, regional gamma diversity, and community dissimilarity (beta diversity) of pollinator taxa were shaped by climate-land-use interactions, while local alpha diversity was solely explained by their additive effects. Pollinator diversity increased with reduced land-use intensity (forest < grassland < arable land < urban) and high flowering-plant diversity at different spatial scales, and higher temperatures homogenized pollinator communities across regions. Our study reveals declines in pollinator diversity with land-use intensity at multiple spatial scales and regional community homogenization in warmer and drier climates. Management options at several scales are highlighted to mitigate impacts of climate change on pollinators and their ecosystem services.}, language = {en} } @article{SponslerKallnikRequieretal.2022, author = {Sponsler, Douglas and Kallnik, Katharina and Requier, Fabrice and Classen, Alice and Maihoff, A. Fabienne and Sieger, Johanna and Steffan-Dewenter, Ingolf}, title = {Floral preferences of mountain bumble bees are constrained by functional traits but flexible through elevation and season}, series = {Oikos}, volume = {2022}, journal = {Oikos}, number = {3}, doi = {10.1111/oik.08902}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259653}, year = {2022}, abstract = {Patterns of resource use by animals can clarify how ecological communities have assembled in the past, how they currently function and how they are likely to respond to future perturbations. Bumble bees (Hymentoptera: Bombus spp.) and their floral hosts provide a diverse yet tractable system in which to explore resource selection in the context of plant-pollinator networks. Under conditions of resource limitation, the ability of bumble bees species to coexist should depend on dietary niche overlap. In this study, we report patterns and dynamics of floral morphotype preferences in a mountain bumble bee community based on ~13 000 observations of bumble bee floral visits recorded along a 1400 m elevation gradient. We found that bumble bees are highly selective generalists, rarely visiting floral morphotypes at the rates predicted by their relative abundances. Preferences also differed markedly across bumble bee species, and these differences were well-explained by variation in bumble bee tongue length, generating patterns of preference similarity that should be expected to predict competition under conditions of resource limitation. Within species, though, morphotype preferences varied by elevation and season, possibly representing adaptive flexibility in response to the high elevational and seasonal turnover of mountain floral communities. Patterns of resource partitioning among bumble bee communities may determine which species can coexist under the altered distributions of bumble bees and their floral hosts caused by climate and land use change.}, language = {en} } @article{ZieglerMeyerOtteetal.2022, author = {Ziegler, Alice and Meyer, Hanna and Otte, Insa and Peters, Marcell K. and Appelhans, Tim and Behler, Christina and B{\"o}hning-Gaese, Katrin and Classen, Alice and Detsch, Florian and Deckert, J{\"u}rgen and Eardley, Connal D. and Ferger, Stefan W. and Fischer, Markus and Gebert, Friederike and Haas, Michael and Helbig-Bonitz, Maria and Hemp, Andreas and Hemp, Claudia and Kakengi, Victor and Mayr, Antonia V. and Ngereza, Christine and Reudenbach, Christoph and R{\"o}der, Juliane and Rutten, Gemma and Schellenberger Costa, David and Schleuning, Matthias and Ssymank, Axel and Steffan-Dewenter, Ingolf and Tardanico, Joseph and Tschapka, Marco and Vollst{\"a}dt, Maximilian G. R. and W{\"o}llauer, Stephan and Zhang, Jie and Brandl, Roland and Nauss, Thomas}, title = {Potential of airborne LiDAR derived vegetation structure for the prediction of animal species richness at Mount Kilimanjaro}, series = {Remote Sensing}, volume = {14}, journal = {Remote Sensing}, number = {3}, issn = {2072-4292}, doi = {10.3390/rs14030786}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262251}, year = {2022}, abstract = {The monitoring of species and functional diversity is of increasing relevance for the development of strategies for the conservation and management of biodiversity. Therefore, reliable estimates of the performance of monitoring techniques across taxa become important. Using a unique dataset, this study investigates the potential of airborne LiDAR-derived variables characterizing vegetation structure as predictors for animal species richness at the southern slopes of Mount Kilimanjaro. To disentangle the structural LiDAR information from co-factors related to elevational vegetation zones, LiDAR-based models were compared to the predictive power of elevation models. 17 taxa and 4 feeding guilds were modeled and the standardized study design allowed for a comparison across the assemblages. Results show that most taxa (14) and feeding guilds (3) can be predicted best by elevation with normalized RMSE values but only for three of those taxa and two of those feeding guilds the difference to other models is significant. Generally, modeling performances between different models vary only slightly for each assemblage. For the remaining, structural information at most showed little additional contribution to the performance. In summary, LiDAR observations can be used for animal species prediction. However, the effort and cost of aerial surveys are not always in proportion with the prediction quality, especially when the species distribution follows zonal patterns, and elevation information yields similar results.}, language = {en} } @article{DannerKellerHaerteletal.2017, author = {Danner, Nadja and Keller, Alexander and H{\"a}rtel, Stephan and Steffan-Dewenter, Ingolf}, title = {Honey bee foraging ecology: Season but not landscape diversity shapes the amount and diversity of collected pollen}, series = {PLoS ONE}, volume = {12}, journal = {PLoS ONE}, number = {8}, doi = {10.1371/journal.pone.0183716}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170424}, pages = {e0183716}, year = {2017}, abstract = {The availability of pollen in agricultural landscapes is essential for the successful growth and reproduction of honey bee colonies (Apis mellifera L.). The quantity and diversity of collected pollen can influence the growth and health of honey bee colonies, but little is known about the influence of landscape structure on pollen diet. In a field experiment, we rotated 16 honey bee colonies across 16 agricultural landscapes, used traps to collect samples of collected pollen and observed intra-colonial dance communication to gain information about foraging distances. DNA metabarcoding was applied to analyze mixed pollen samples. Neither the amount of collected pollen nor pollen diversity was related to landscape diversity. However, we found a strong seasonal variation in the amount and diversity of collected pollen in all sites independent of landscape diversity. The observed increase in foraging distances with decreasing landscape diversity suggests that honey bees compensated for lower landscape diversity by increasing their pollen foraging range in order to maintain pollen amount and diversity. Our results underscore the importance of a diverse pollen diet for honey bee colonies. Agri-environmental schemes aiming to support pollinators should focus on possible spatial and temporal gaps in pollen availability and diversity in agricultural landscapes.}, language = {en} } @article{FrickeSteffanDewenterZhangetal.2022, author = {Fricke, Ute and Steffan-Dewenter, Ingolf and Zhang, Jie and Tobisch, Cynthia and Rojas-Botero, Sandra and Benjamin, Caryl S. and Englmeier, Jana and Ganuza, Cristina and Haensel, Maria and Riebl, Rebekka and Uhler, Johannes and Uphus, Lars and Ewald, J{\"o}rg and Kollmann, Johannes and Redlich, Sarah}, title = {Landscape diversity and local temperature, but not climate, affect arthropod predation among habitat types}, series = {PLoS ONE}, volume = {17}, journal = {PLoS ONE}, number = {4}, doi = {10.1371/journal.pone.0264881}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301292}, year = {2022}, abstract = {Arthropod predators are important for ecosystem functioning by providing top-down regulation of insect herbivores. As predator communities and activity are influenced by biotic and abiotic factors on different spatial scales, the strength of top-down regulation ('arthropod predation') is also likely to vary. Understanding the combined effects of potential drivers on arthropod predation is urgently needed with regard to anthropogenic climate and land-use change. In a large-scale study, we recorded arthropod predation rates using artificial caterpillars on 113 plots of open herbaceous vegetation embedded in contrasting habitat types (forest, grassland, arable field, settlement) along climate and land-use gradients in Bavaria, Germany. As potential drivers we included habitat characteristics (habitat type, plant species richness, local mean temperature and mean relative humidity during artificial caterpillar exposure), landscape diversity (0.5-3.0-km, six scales), climate (multi-annual mean temperature, 'MAT') and interactive effects of habitat type with other drivers. We observed no substantial differences in arthropod predation rates between the studied habitat types, related to plant species richness and across the Bavarian-wide climatic gradient, but predation was limited when local mean temperatures were low and tended to decrease towards higher relative humidity. Arthropod predation rates increased towards more diverse landscapes at a 2-km scale. Interactive effects of habitat type with local weather conditions, plant species richness, landscape diversity and MAT were not observed. We conclude that landscape diversity favours high arthropod predation rates in open herbaceous vegetation independent of the dominant habitat in the vicinity. This finding may be harnessed to improve top-down control of herbivores, e.g. agricultural pests, but further research is needed for more specific recommendations on landscape management. The absence of MAT effects suggests that high predation rates may occur independent of moderate increases of MAT in the near future.}, language = {en} } @article{RedlichZhangBenjaminetal.2022, author = {Redlich, Sarah and Zhang, Jie and Benjamin, Caryl and Dhillon, Maninder Singh and Englmeier, Jana and Ewald, J{\"o}rg and Fricke, Ute and Ganuza, Cristina and Haensel, Maria and Hovestadt, Thomas and Kollmann, Johannes and Koellner, Thomas and K{\"u}bert-Flock, Carina and Kunstmann, Harald and Menzel, Annette and Moning, Christoph and Peters, Wibke and Riebl, Rebekka and Rummler, Thomas and Rojas-Botero, Sandra and Tobisch, Cynthia and Uhler, Johannes and Uphus, Lars and M{\"u}ller, J{\"o}rg and Steffan-Dewenter, Ingolf}, title = {Disentangling effects of climate and land use on biodiversity and ecosystem services—A multi-scale experimental design}, series = {Methods in Ecology and Evolution}, volume = {13}, journal = {Methods in Ecology and Evolution}, number = {2}, doi = {10.1111/2041-210X.13759}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258270}, pages = {514-527}, year = {2022}, abstract = {Climate and land-use change are key drivers of environmental degradation in the Anthropocene, but too little is known about their interactive effects on biodiversity and ecosystem services. Long-term data on biodiversity trends are currently lacking. Furthermore, previous ecological studies have rarely considered climate and land use in a joint design, did not achieve variable independence or lost statistical power by not covering the full range of environmental gradients. Here, we introduce a multi-scale space-for-time study design to disentangle effects of climate and land use on biodiversity and ecosystem services. The site selection approach coupled extensive GIS-based exploration (i.e. using a Geographic information system) and correlation heatmaps with a crossed and nested design covering regional, landscape and local scales. Its implementation in Bavaria (Germany) resulted in a set of study plots that maximise the potential range and independence of environmental variables at different spatial scales. Stratifying the state of Bavaria into five climate zones (reference period 1981-2010) and three prevailing land-use types, that is, near-natural, agriculture and urban, resulted in 60 study regions (5.8 × 5.8 km quadrants) covering a mean annual temperature gradient of 5.6-9.8°C and a spatial extent of ~310 × 310 km. Within these regions, we nested 180 study plots located in contrasting local land-use types, that is, forests, grasslands, arable land or settlement (local climate gradient 4.5-10°C). This approach achieved low correlations between climate and land use (proportional cover) at the regional and landscape scale with |r ≤ 0.33| and |r ≤ 0.29| respectively. Furthermore, using correlation heatmaps for local plot selection reduced potentially confounding relationships between landscape composition and configuration for plots located in forests, arable land and settlements. The suggested design expands upon previous research in covering a significant range of environmental gradients and including a diversity of dominant land-use types at different scales within different climatic contexts. It allows independent assessment of the relative contribution of multi-scale climate and land use on biodiversity and ecosystem services. Understanding potential interdependencies among global change drivers is essential to develop effective restoration and mitigation strategies against biodiversity decline, especially in expectation of future climatic changes. Importantly, this study also provides a baseline for long-term ecological monitoring programs.}, language = {en} } @article{RequierJowanowitschKallniketal.2020, author = {Requier, Fabrice and Jowanowitsch, Kim K. and Kallnik, Katharina and Steffan-Dewenter, Ingolf}, title = {Limitation of complementary resources affects colony growth, foraging behavior, and reproduction in bumble bees}, series = {Ecology}, volume = {101}, journal = {Ecology}, number = {3}, doi = {10.1002/ecy.2946}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211891}, pages = {e02946}, year = {2020}, abstract = {Resource availability in agricultural landscapes has been disturbed for many organisms, including pollinator species. Abundance and diversity in flower availability benefit bee populations; however, little is known about which of protein or carbohydrate resources may limit their growth and reproductive performance. Here, we test the hypothesis of complementary resource limitation using a supplemental feeding approach. We applied this assumption with bumble bees (Bombus terrestris), assuming that colony growth and reproductive performance should depend on the continuous supply of carbohydrates and proteins, through the foraging for nectar and pollen, respectively. We placed wild-caught bumble bee colonies along a landscape gradient of seminatural habitats, and monitored the colonies' weight, foraging activity, and reproductive performance during the whole colony cycle. We performed supplemental feeding as an indicator of landscape resource limitation, using a factorial design consisting of the addition of sugar water (carbohydrate, supplemented or not) crossed by pollen (protein, supplemented or not). Bumble bee colony dynamics showed a clear seasonal pattern with a period of growth followed by a period of stagnation. Higher abundance of seminatural habitats resulted in reducing the proportion of pollen foragers relative to all foragers in both periods, and in improving the reproductive performance of bumble bees. Interestingly, the supplemental feeding of sugar water positively affected the colony weight during the stagnation period, and the supplemental feeding of pollen mitigated the landscape effect on pollen collection investment. Single and combined supplementation of sugar water and pollen increased the positive effect of seminatural habitats on reproductive performance. This study reveals a potential colimitation in pollen and nectar resources affecting foraging behavior and reproductive performance in bumble bees, and indicates that even in mixed agricultural landscapes with higher proportions of seminatural habitats, bumble bee populations face resource limitations. We conclude that the seasonal management of floral resources must be considered in conservation to support bumble bee populations and pollination services in farmlands.}, language = {en} } @article{DuquePoelmanSteffanDewenter2019, author = {Duque, Laura and Poelman, Erik H. and Steffan-Dewenter, Ingolf}, title = {Plant-mediated effects of ozone on herbivores depend on exposure duration and temperature}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-56234-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202805}, pages = {19891}, year = {2019}, abstract = {Abiotic stress by elevated tropospheric ozone and temperature can alter plants' metabolism, growth, and nutritional value and modify the life cycle of their herbivores. We investigated how the duration of exposure of Sinapis arvensis plants to high ozone and temperature levels affect the life cycle of the large cabbage white, Pieris brassicae. Plants were exposed to ozone-clean (control) or ozone-enriched conditions (120 ppb) for either 1 or 5 days and were afterwards kept in a greenhouse with variable temperature conditions. When given the choice, P. brassicae butterflies laid 49\% fewer eggs on ozone-exposed than on control plants when the exposure lasted for 5 days, but showed no preference when exposure lasted for 1 day. The caterpillars took longer to hatch on ozone-exposed plants and at lower ambient temperatures. The ozone treatment had a positive effect on the survival of the eggs. Ozone decreased the growth of caterpillars reared at higher temperatures on plants exposed for 5 days, but not on plants exposed for 1 day. Overall, longer exposure of the plants to ozone and higher temperatures affected the life cycle of the herbivore more strongly. With global warming, the indirect impacts of ozone on herbivores are likely to become more common.}, language = {en} } @article{ClassenEardleyHempetal.2020, author = {Classen, Alice and Eardley, Connal D. and Hemp, Andreas and Peters, Marcell K. and Peters, Ralph S. and Ssymank, Axel and Steffan-Dewenter, Ingolf}, title = {Specialization of plant-pollinator interactions increases with temperature at Mt. Kilimanjaro}, series = {Ecology and Evolution}, volume = {10}, journal = {Ecology and Evolution}, number = {4}, doi = {10.1002/ece3.6056}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235959}, pages = {2182-2195}, year = {2020}, abstract = {Aim: Species differ in their degree of specialization when interacting with other species, with significant consequences for the function and robustness of ecosystems. In order to better estimate such consequences, we need to improve our understanding of the spatial patterns and drivers of specialization in interaction networks. Methods: Here, we used the extensive environmental gradient of Mt. Kilimanjaro (Tanzania, East Africa) to study patterns and drivers of specialization, and robustness of plant-pollinator interactions against simulated species extinction with standardized sampling methods. We studied specialization, network robustness and other network indices of 67 quantitative plant-pollinator networks consisting of 268 observational hours and 4,380 plant-pollinator interactions along a 3.4 km elevational gradient. Using path analysis, we tested whether resource availability, pollinator richness, visitation rates, temperature, and/or area explain average specialization in pollinator communities. We further linked pollinator specialization to different pollinator taxa, and species traits, that is, proboscis length, body size, and species elevational ranges. Results: We found that specialization decreased with increasing elevation at different levels of biological organization. Among all variables, mean annual temperature was the best predictor of average specialization in pollinator communities. Specialization differed between pollinator taxa, but was not related to pollinator traits. Network robustness against simulated species extinctions of both plants and pollinators was lowest in the most specialized interaction networks, that is, in the lowlands. Conclusions: Our study uncovers patterns in plant-pollinator specialization along elevational gradients. Mean annual temperature was closely linked to pollinator specialization. Energetic constraints, caused by short activity timeframes in cold highlands, may force ectothermic species to broaden their dietary spectrum. Alternatively or in addition, accelerated evolutionary rates might facilitate the establishment of specialization under warm climates. Despite the mechanisms behind the patterns have yet to be fully resolved, our data suggest that temperature shifts in the course of climate change may destabilize pollination networks by affecting network architecture.}, language = {en} } @article{VoulgariKokotaSteffanDewenterKeller2020, author = {Voulgari-Kokota, Anna and Steffan-Dewenter, Ingolf and Keller, Alexander}, title = {Susceptibility of Red Mason Bee Larvae to Bacterial Threats Due to Microbiome Exchange with Imported Pollen Provisions}, series = {Insects}, volume = {11}, journal = {Insects}, number = {6}, issn = {2075-4450}, doi = {10.3390/insects11060373}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207948}, year = {2020}, abstract = {Solitary bees are subject to a variety of pressures that cause severe population declines. Currently, habitat loss, temperature shifts, agrochemical exposure, and new parasites are identified as major threats. However, knowledge about detrimental bacteria is scarce, although they may disturb natural microbiomes, disturb nest environments, or harm the larvae directly. To address this gap, we investigated 12 Osmia bicornis nests with deceased larvae and 31 nests with healthy larvae from the same localities in a 16S ribosomal RNA (rRNA) gene metabarcoding study. We sampled larvae, pollen provisions, and nest material and then contrasted bacterial community composition and diversity in healthy and deceased nests. Microbiomes of pollen provisions and larvae showed similarities for healthy larvae, whilst this was not the case for deceased individuals. We identified three bacterial taxa assigned to Paenibacillus sp. (closely related to P. pabuli/amylolyticus/xylanexedens), Sporosarcina sp., and Bacillus sp. as indicative for bacterial communities of deceased larvae, as well as Lactobacillus for corresponding pollen provisions. Furthermore, we performed a provisioning experiment, where we fed larvae with untreated and sterilized pollens, as well as sterilized pollens inoculated with a Bacillus sp. isolate from a deceased larva. Untreated larval microbiomes were consistent with that of the pollen provided. Sterilized pollen alone did not lead to acute mortality, while no microbiome was recoverable from the larvae. In the inoculation treatment, we observed that larval microbiomes were dominated by the seeded bacterium, which resulted in enhanced mortality. These results support that larval microbiomes are strongly determined by the pollen provisions. Further, they underline the need for further investigation of the impact of detrimental bacterial acquired via pollens and potential buffering by a diverse pollen provision microbiome in solitary bees.}, language = {en} } @article{DhillonDahmsKuebertFlocketal.2023, author = {Dhillon, Maninder Singh and Dahms, Thorsten and Kuebert-Flock, Carina and Rummler, Thomas and Arnault, Joel and Steffan-Dewenter, Ingolf and Ullmann, Tobias}, title = {Integrating random forest and crop modeling improves the crop yield prediction of winter wheat and oil seed rape}, series = {Frontiers in Remote Sensing}, volume = {3}, journal = {Frontiers in Remote Sensing}, issn = {2673-6187}, doi = {10.3389/frsen.2022.1010978}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301462}, year = {2023}, abstract = {The fast and accurate yield estimates with the increasing availability and variety of global satellite products and the rapid development of new algorithms remain a goal for precision agriculture and food security. However, the consistency and reliability of suitable methodologies that provide accurate crop yield outcomes still need to be explored. The study investigates the coupling of crop modeling and machine learning (ML) to improve the yield prediction of winter wheat (WW) and oil seed rape (OSR) and provides examples for the Free State of Bavaria (70,550 km2), Germany, in 2019. The main objectives are to find whether a coupling approach [Light Use Efficiency (LUE) + Random Forest (RF)] would result in better and more accurate yield predictions compared to results provided with other models not using the LUE. Four different RF models [RF1 (input: Normalized Difference Vegetation Index (NDVI)), RF2 (input: climate variables), RF3 (input: NDVI + climate variables), RF4 (input: LUE generated biomass + climate variables)], and one semi-empiric LUE model were designed with different input requirements to find the best predictors of crop monitoring. The results indicate that the individual use of the NDVI (in RF1) and the climate variables (in RF2) could not be the most accurate, reliable, and precise solution for crop monitoring; however, their combined use (in RF3) resulted in higher accuracies. Notably, the study suggested the coupling of the LUE model variables to the RF4 model can reduce the relative root mean square error (RRMSE) from -8\% (WW) and -1.6\% (OSR) and increase the R 2 by 14.3\% (for both WW and OSR), compared to results just relying on LUE. Moreover, the research compares models yield outputs by inputting three different spatial inputs: Sentinel-2(S)-MOD13Q1 (10 m), Landsat (L)-MOD13Q1 (30 m), and MOD13Q1 (MODIS) (250 m). The S-MOD13Q1 data has relatively improved the performance of models with higher mean R 2 [0.80 (WW), 0.69 (OSR)], and lower RRMSE (\%) (9.18, 10.21) compared to L-MOD13Q1 (30 m) and MOD13Q1 (250 m). Satellite-based crop biomass, solar radiation, and temperature are found to be the most influential variables in the yield prediction of both crops.}, language = {en} } @article{KrimmerMartinHolzschuhetal.2022, author = {Krimmer, Elena and Martin, Emily A. and Holzschuh, Andrea and Krauss, Jochen and Steffan-Dewenter, Ingolf}, title = {Flower fields and pesticide use interactively shape pollen beetle infestation and parasitism in oilseed rape fields}, series = {Journal of Applied Ecology}, volume = {59}, journal = {Journal of Applied Ecology}, number = {1}, doi = {10.1111/1365-2664.14051}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258037}, pages = {263-273}, year = {2022}, abstract = {Pollen beetles (Brassicogethes spp.) are the main pests of oilseed rape (OSR, Brassica napus) in Europe and responsible for massive yield losses. Upcoming pesticide resistances highlight the need for other means of crop protection, such as natural pest control. Sown flower fields aim to counteract the decrease of insect biodiversity in agricultural landscapes by providing resources to ecosystem service providers. However, the optimal age and size of flower fields to increase natural pest control is still unclear. We conducted experiments on 31 OSR fields located along a gradient of landscape-scale semi-natural habitat (SNH). OSR fields were located adjacent to flower fields which differed in age, continuity and size, or adjacent to crop fields or calcareous grasslands. Pesticide-free areas were established to examine interactive effects of pesticide use and flower field characteristics. The abundance of pollen beetle adults and larvae, parasitism and superparasitism rates in OSR were recorded at increasing distances to the adjacent sites. Flower fields and calcareous grasslands increased pollen beetle parasitism when compared to OSR fields neighbouring crop fields. The threshold for effective natural pest control of 35\% could be reached in the pesticide-free areas of OSR fields adjacent to calcareous grasslands and flower fields maintained continuously for at least 6 years. In pesticide-sprayed areas, pollen beetle parasitism and superparasitism declined with increasing distance to the adjacent field. Furthermore, flower fields larger than 1.5 ha were able to improve pollen beetle parasitism more than smaller fields. Synthesis and applications. To promote natural pest control in oilseed rape (OSR), large flower fields should be maintained for several years, to create stable habitats for natural enemies. The continuous maintenance of flower fields should be preferred, as ploughing and resowing after 5-6 years decreased the positive effects of the flower fields on natural pest control in adjacent OSR fields. However, pesticide use can abrogate positive effects of flower fields on pollen beetle parasitism. This study highlights that sown flower fields have the potential to increase natural pest control in OSR, but this potential is depending on its age, continuity and size and can be hindered by pesticide use.}, language = {en} } @article{BeerSteffanDewenterHaerteletal.2016, author = {Beer, Katharina and Steffan-Dewenter, Ingolf and H{\"a}rtel, Stephan and Helfrich-F{\"o}rster, Charlotte}, title = {A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior}, series = {Journal of Comparative Physiology A}, volume = {202}, journal = {Journal of Comparative Physiology A}, number = {8}, doi = {10.1007/s00359-016-1103-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188030}, pages = {555-565}, year = {2016}, abstract = {Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light-dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees.}, language = {en} } @article{SteijvenSpaetheSteffanDewenteretal.2017, author = {Steijven, Karin and Spaethe, Johannes and Steffan-Dewenter, Ingolf and H{\"a}rtel, Stephan}, title = {Learning performance and brain structure of artificially-reared honey bees fed with different quantities of food}, series = {PeerJ}, volume = {5}, journal = {PeerJ}, number = {e3858}, doi = {10.7717/peerj.3858}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170137}, year = {2017}, abstract = {Background Artificial rearing of honey bee larvae is an established method which enables to fully standardize the rearing environment and to manipulate the supplied diet to the brood. However, there are no studies which compare learning performance or neuroanatomic differences of artificially-reared (in-lab) bees in comparison with their in-hive reared counterparts. Methods Here we tested how different quantities of food during larval development affect body size, brain morphology and learning ability of adult honey bees. We used in-lab rearing to be able to manipulate the total quantity of food consumed during larval development. After hatching, a subset of the bees was taken for which we made 3D reconstructions of the brains using confocal laser-scanning microscopy. Learning ability and memory formation of the remaining bees was tested in a differential olfactory conditioning experiment. Finally, we evaluated how bees reared with different quantities of artificial diet compared to in-hive reared bees. Results Thorax and head size of in-lab reared honey bees, when fed the standard diet of 160 µl or less, were slightly smaller than hive bees. The brain structure analyses showed that artificially reared bees had smaller mushroom body (MB) lateral calyces than their in-hive counterparts, independently of the quantity of food they received. However, they showed the same total brain size and the same associative learning ability as in-hive reared bees. In terms of mid-term memory, but not early long-term memory, they performed even better than the in-hive control. Discussion We have demonstrated that bees that are reared artificially (according to the Aupinel protocol) and kept in lab-conditions perform the same or even better than their in-hive sisters in an olfactory conditioning experiment even though their lateral calyces were consistently smaller at emergence. The applied combination of experimental manipulation during the larval phase plus subsequent behavioral and neuro-anatomic analyses is a powerful tool for basic and applied honey bee research.}, language = {en} } @article{LaswayKinaboMremietal.2021, author = {Lasway, Julius V. and Kinabo, Neema R. and Mremi, Rudolf F. and Martin, Emanuel H. and Nyakunga, Oliver C. and Sanya, John J. and Rwegasira, Gration M. and Lesio, Nicephor and Gideon, Hulda and Pauly, Alain and Eardley, Connal and Peters, Marcell K. and Peterson, Andrew T. and Steffan-Dewenter, Ingolf and Njovu, Henry K.}, title = {A synopsis of the Bee occurrence data of northern Tanzania}, series = {Biodiversity Data Journal}, volume = {9}, journal = {Biodiversity Data Journal}, doi = {10.3897/BDJ.9.e68190}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265018}, year = {2021}, abstract = {Background Bees (Hymenoptera: Apoidea: Anthophila) are the most important group of pollinators with about 20,507 known species worldwide. Despite the critical role of bees in providing pollination services, studies aiming at understanding which species are present across disturbance gradients are scarce. Limited taxononomic information for the existing and unidentified bee species in Tanzania make their conservation haphazard. Here, we present a dataset of bee species records obtained from a survey in nothern Tanzania i.e. Kilimanjaro, Arusha and Manyara regions. Our findings serve as baseline data necessary for understanding the diversity and distribution of bees in the northern parts of the country, which is a critical step in devising robust conservation and monitoring strategies for their populations. New information In this paper, we present information on 45 bee species belonging to 20 genera and four families sampled using a combination of sweep-netting and pan trap methods. Most species (27, ~ 60\%) belong to the family Halictidae followed by 16 species (35.5\%) from the family Apidae. Megachilidae and Andrenidae were the least represented, each with only one species (2.2\%). Additional species of Apidae and Megachilidae sampled during this survey are not yet published on Global Biodiversity Information Facility (GBIF), once they will be available on GBIF, they will be published in a subsequent paper. From a total of 953 occurrences, highest numbers were recorded in Kilimanjaro Region (n = 511), followed by Arusha (n = 410) and Manyara (n = 32), but this pattern reflects the sampling efforts of the research project rather than real bias in the distributions of bee species in northern Tanzania.}, language = {en} } @article{MayrKellerPetersetal.2021, author = {Mayr, Antonia V. and Keller, Alexander and Peters, Marcell K. and Grimmer, Gudrun and Krischke, Beate and Geyer, Mareen and Schmitt, Thomas and Steffan-Dewenter, Ingolf}, title = {Cryptic species and hidden ecological interactions of halictine bees along an elevational gradient}, series = {Ecology and Evolution}, volume = {11}, journal = {Ecology and Evolution}, number = {12}, doi = {10.1002/ece3.7605}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-238853}, pages = {7700 -- 7712}, year = {2021}, abstract = {Changes of abiotic and biotic conditions along elevational gradients represent serious challenges to organisms which may promote the turnover of species, traits and biotic interaction partners. Here, we used molecular methods to study cuticular hydrocarbon (CHC) profiles, biotic interactions and phylogenetic relationships of halictid bees of the genus Lasioglossum along a 2,900 m elevational gradient at Mt. Kilimanjaro, Tanzania. We detected a strong species turnover of morphologically indistinguishable taxa with phylogenetically clustered cryptic species at high elevations, changes in CHC profiles, pollen resource diversity, and a turnover in the gut and body surface microbiome of bees. At high elevations, increased proportions of saturated compounds in CHC profiles indicate physiological adaptations to prevent desiccation. More specialized diets with higher proportions of low-quality Asteraceae pollen imply constraints in the availability of food resources. Interactive effects of climatic conditions on gut and surface microbiomes, CHC profiles, and pollen diet suggest complex feedbacks among abiotic conditions, ecological interactions, physiological adaptations, and phylogenetic constraints as drivers of halictid bee communities at Mt. Kilimanjaro.}, language = {en} } @article{DuquePoelmanSteffanDewenter2021, author = {Duque, Laura and Poelman, Erik H. and Steffan-Dewenter, Ingolf}, title = {Plant age at the time of ozone exposure affects flowering patterns, biotic interactions and reproduction of wild mustard}, series = {Scientific Reports}, volume = {11}, journal = {Scientific Reports}, number = {1}, doi = {10.1038/s41598-021-02878-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265742}, year = {2021}, abstract = {Exposure of plants to environmental stressors can modify their metabolism, interactions with other organisms and reproductive success. Tropospheric ozone is a source of plant stress. We investigated how an acute exposure to ozone at different times of plant development affects reproductive performance, as well as the flowering patterns and the interactions with pollinators and herbivores, of wild mustard plants. The number of open flowers was higher on plants exposed to ozone at earlier ages than on the respective controls, while plants exposed at later ages showed a tendency for decreased number of open flowers. The changes in the number of flowers provided a good explanation for the ozone-induced effects on reproductive performance and on pollinator visitation. Ozone exposure at earlier ages also led to either earlier or extended flowering periods. Moreover, ozone tended to increase herbivore abundance, with responses depending on herbivore taxa and the plant age at the time of ozone exposure. These results suggest that the effects of ozone exposure depend on the developmental stage of the plant, affecting the flowering patterns in different directions, with consequences for pollination and reproduction of annual crops and wild species.}, language = {en} } @article{UhlerRedlichZhangetal.2021, author = {Uhler, Johannes and Redlich, Sarah and Zhang, Jie and Hothorn, Torsten and Tobisch, Cynthia and Ewald, J{\"o}rg and Thorn, Simon and Seibold, Sebastian and Mitesser, Oliver and Morin{\`e}re, J{\´e}r{\^o}me and Bozicevic, Vedran and Benjamin, Caryl S. and Englmeier, Jana and Fricke, Ute and Ganuza, Cristina and Haensel, Maria and Riebl, Rebekka and Rojas-Botero, Sandra and Rummler, Thomas and Uphus, Lars and Schmidt, Stefan and Steffan-Dewenter, Ingolf and M{\"u}ller, J{\"o}rg}, title = {Relationships of insect biomass and richness with land use along a climate gradient}, series = {Nature Communications}, volume = {12}, journal = {Nature Communications}, number = {1}, doi = {10.1038/s41467-021-26181-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265058}, year = {2021}, abstract = {Recently reported insect declines have raised both political and social concern. Although the declines have been attributed to land use and climate change, supporting evidence suffers from low taxonomic resolution, short time series, a focus on local scales, and the collinearity of the identified drivers. In this study, we conducted a systematic assessment of insect populations in southern Germany, which showed that differences in insect biomass and richness are highly context dependent. We found the largest difference in biomass between semi-natural and urban environments (-42\%), whereas differences in total richness (-29\%) and the richness of threatened species (-56\%) were largest from semi-natural to agricultural environments. These results point to urbanization and agriculture as major drivers of decline. We also found that richness and biomass increase monotonously with increasing temperature, independent of habitat. The contrasting patterns of insect biomass and richness question the use of these indicators as mutual surrogates. Our study provides support for the implementation of more comprehensive measures aimed at habitat restoration in order to halt insect declines.}, language = {en} } @article{NjovuSteffanDewenterGebertetal.2021, author = {Njovu, Henry K. and Steffan-Dewenter, Ingolf and Gebert, Friederike and Schellenberger Costa, David and Kleyer, Michael and Wagner, Thomas and Peters, Marcell K.}, title = {Plant traits mediate the effects of climate on phytophagous beetle diversity on Mt. Kilimanjaro}, series = {Ecology}, volume = {102}, journal = {Ecology}, number = {12}, doi = {10.1002/ecy.3521}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257343}, year = {2021}, abstract = {Patterns of insect diversity along elevational gradients are well described in ecology. However, it remains little tested how variation in the quantity, quality, and diversity of food resources influence these patterns. Here we analyzed the direct and indirect effects of climate, food quantity (estimated by net primary productivity), quality (variation in the specific leaf area index, leaf nitrogen to phosphorus and leaf carbon to nitrogen ratio), and food diversity (diversity of leaf traits) on the species richness of phytophagous beetles along the broad elevation and land use gradients of Mt. Kilimanjaro, Tanzania. We sampled beetles at 65 study sites located in both natural and anthropogenic habitats, ranging from 866 to 4,550 m asl. We used path analysis to unravel the direct and indirect effects of predictor variables on species richness. In total, 3,154 phytophagous beetles representing 19 families and 304 morphospecies were collected. We found that the species richness of phytophagous beetles was bimodally distributed along the elevation gradient with peaks at the lowest (˜866 m asl) and upper mid-elevations (˜3,200 m asl) and sharply declined at higher elevations. Path analysis revealed temperature- and climate-driven changes in primary productivity and leaf trait diversity to be the best predictors of changes in the species richness of phytophagous beetles. Species richness increased with increases in mean annual temperature, primary productivity, and with increases in the diversity of leaf traits of local ecosystems. Our study demonstrates that, apart from temperature, the quantity and diversity of food resources play a major role in shaping diversity gradients of phytophagous insects. Drivers of global change, leading to a change of leaf traits and causing reductions in plant diversity and productivity, may consequently reduce the diversity of herbivore assemblages.}, language = {en} } @article{DaineseSchneiderKraussetal.2017, author = {Dainese, Matteo and Schneider, Gudrun and Krauss, Jochen and Steffan-Dewenter, Ingolf}, title = {Complementarity among natural enemies enhances pest suppression}, series = {Scientific Reports}, volume = {7}, journal = {Scientific Reports}, doi = {10.1038/s41598-017-08316-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158621}, pages = {8172}, year = {2017}, abstract = {Natural enemies have been shown to be effective agents for controlling insect pests in crops. However, it remains unclear how different natural enemy guilds contribute to the regulation of pests and how this might be modulated by landscape context. In a field exclusion experiment in oilseed rape (OSR), we found that parasitoids and ground-dwelling predators acted in a complementary way to suppress pollen beetles, suggesting that pest control by multiple enemies attacking a pest during different periods of its occurrence in the field improves biological control efficacy. The density of pollen beetle significantly decreased with an increased proportion of non-crop habitats in the landscape. Parasitism had a strong effect on pollen beetle numbers in landscapes with a low or intermediate proportion of non-crop habitats, but not in complex landscapes. Our results underline the importance of different natural enemy guilds to pest regulation in crops, and demonstrate how biological control can be strengthened by complementarity among natural enemies. The optimization of natural pest control by adoption of specific management practices at local and landscape scales, such as establishing non-crop areas, low-impact tillage, and temporal crop rotation, could significantly reduce dependence on pesticides and foster yield stability through ecological intensification in agriculture.}, language = {en} } @article{RedlichMartinSteffan‐Dewenter2021, author = {Redlich, Sarah and Martin, Emily A. and Steffan-Dewenter, Ingolf}, title = {Sustainable landscape, soil and crop management practices enhance biodiversity and yield in conventional cereal systems}, series = {Journal of Applied Ecology}, volume = {58}, journal = {Journal of Applied Ecology}, number = {3}, doi = {10.1111/1365-2664.13821}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-228345}, pages = {507 -- 517}, year = {2021}, abstract = {Input-driven, modern agriculture is commonly associated with large-scale threats to biodiversity, the disruption of ecosystem services and long-term risks to food security and human health. A switch to more sustainable yet highly productive farming practices seems unavoidable. However, an integrative evaluation of targeted management schemes at field and landscape scales is currently lacking. Furthermore, the often-disproportionate influence of soil conditions and agrochemicals on yields may mask the benefits of biodiversity-driven ecosystem services. Here, we used a real-world ecosystem approach to identify sustainable management practices for enhanced functional biodiversity and yield on 28 temperate wheat fields. Using path analysis, we assessed direct and indirect links between soil, crop and landscape management with natural enemies and pests, as well as follow-on effects on yield quantity and quality. A paired-field design with a crossed insecticide-fertilizer experiment allowed us to control for the relative influence of soil characteristics and agrochemical inputs. We demonstrate that biodiversity-enhancing management options such as reduced tillage, crop rotation diversity and small field size can enhance natural enemies without relying on agrochemical inputs. Similarly, we show that in this system controlling pests and weeds by agrochemical means is less relevant than expected for final crop productivity. Synthesis and applications. Our study highlights soil, crop and landscape management practices that can enhance beneficial biodiversity while reducing agrochemical usage and negative environmental impacts of conventional agriculture. The diversification of cropping systems and conservation tillage are practical measures most farmers can implement without productivity losses. Combining local measures with improved landscape management may also strengthen the sustainability and resilience of cropping systems in light of future global change.}, language = {en} } @article{MayrPetersEardleyetal.2020, author = {Mayr, Antonia V. and Peters, Marcell K. and Eardley, Connal D. and Renner, Marion E. and R{\"o}der, Juliane and Steffan-Dewenter, Ingolf}, title = {Climate and food resources shape species richness and trophic interactions of cavity-nesting Hymenoptera}, series = {Journal of Biogeography}, volume = {47}, journal = {Journal of Biogeography}, number = {4}, doi = {10.1111/jbi.13753}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208101}, pages = {854-865}, year = {2020}, abstract = {Aim: Temperature, food resources and top-down regulation by antagonists are considered as major drivers of insect diversity, but their relative importance is poorly understood. Here, we used cavity-nesting communities of bees, wasps and their antagonists to reveal the role of temperature, food resources, parasitism rate and land use as drivers of species richness at different trophic levels along a broad elevational gradient. Location: Mt. Kilimanjaro, Tanzania. Taxon: Cavity-nesting Hymenoptera (Hymenoptera: Apidae, Colletidae, Megachilidae, Crabronidae, Sphecidae, Pompilidae, Vespidae). Methods: We established trap nests on 25 study sites that were distributed over similar large distances in terms of elevation along an elevational gradient from 866 to 1788 m a.s.l., including both natural and disturbed habitats. We quantified species richness and abundance of bees, wasps and antagonists, parasitism rates and flower or arthropod food resources. Data were analysed with generalized linear models within a multi-model inference framework. Results: Elevational species richness patterns changed with trophic level from monotonically declining richness of bees to increasingly humped-shaped patterns for caterpillar-hunting wasps, spider-hunting wasps and antagonists. Parasitism rates generally declined with elevation but were higher for wasps than for bees. Temperature was the most important predictor of both bee and wasp host richness patterns. Antagonist richness patterns were also well predicted by temperature, but in contrast to host richness patterns, additionally by resource abundance and diversity. The conversion of natural habitats through anthropogenic land use, which included biomass removal, agricultural inputs, vegetation structure and percentage of surrounding agricultural habitats, had no significant effects on bee and wasp communities. Main conclusions: Our study underpins the importance of temperature as a main driver of diversity gradients in ectothermic organisms and reveals the increasingly important role of food resources at higher trophic levels. Higher parasitism rates at higher trophic levels and at higher temperatures indicated that the relative importance of bottom-up and top-down drivers of species richness change across trophic levels and may respond differently to future climate change.}, language = {en} } @article{PetersClassenMuelleretal.2020, author = {Peters, Marcell K. and Classen, Alice and M{\"u}ller, J{\"o}rg and Steffan‑Dewenter, Ingolf}, title = {Increasing the phylogenetic coverage for understanding broad-scale diversity gradients}, series = {Oecologia}, volume = {192}, journal = {Oecologia}, issn = {0029-8549}, doi = {10.1007/s00442-020-04615-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232519}, pages = {629-639}, year = {2020}, abstract = {Despite decades of scientific effort, there is still no consensus on the determinants of broad-scale gradients of animal diver-sity. We argue that general drivers of diversity are unlikely to be found among the narrowly defined taxa which are typically analyzed in studies of broad-scale diversity gradients because ecological niches evolve largely conservatively. This causes constraints in the use of available niche space leading to systematic differences in diversity gradients among taxa. We instead advocate studies of phylogenetically diverse animal communities along broad environmental gradients. Such multi-taxa communities are less constrained in resource use and diversification and may be better targets for testing major classical hypotheses on diversity gradients. Besides increasing the spatial scale in analyses, expanding the phylogenetic coverage may be a second way to achieve higher levels of generality in studies of broad-scale diversity gradients}, language = {en} } @article{NuernbergerSteffanDewenterHaertel2017, author = {N{\"u}rnberger, Fabian and Steffan-Dewenter, Ingolf and H{\"a}rtel, Stephan}, title = {Combined effects of waggle dance communication and landscape heterogeneity on nectar and pollen uptake in honey bee colonies}, series = {PeerJ}, volume = {5}, journal = {PeerJ}, number = {e3441}, doi = {10.7717/peerj.3441}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170813}, year = {2017}, abstract = {The instructive component of waggle dance communication has been shown to increase resource uptake of Apis mellifera colonies in highly heterogeneous resource environments, but an assessment of its relevance in temperate landscapes with different levels of resource heterogeneity is currently lacking. We hypothesized that the advertisement of resource locations via dance communication would be most relevant in highly heterogeneous landscapes with large spatial variation of floral resources. To test our hypothesis, we placed 24 Apis mellifera colonies with either disrupted or unimpaired instructive component of dance communication in eight Central European agricultural landscapes that differed in heterogeneity and resource availability. We monitored colony weight change and pollen harvest as measure of foraging success. Dance disruption did not significantly alter colony weight change, but decreased pollen harvest compared to the communicating colonies by 40\%. There was no general effect of resource availability on nectar or pollen foraging success, but the effect of landscape heterogeneity on nectar uptake was stronger when resource availability was high. In contrast to our hypothesis, the effects of disrupted bee communication on nectar and pollen foraging success were not stronger in landscapes with heterogeneous compared to homogenous resource environments. Our results indicate that in temperate regions intra-colonial communication of resource locations benefits pollen foraging more than nectar foraging, irrespective of landscape heterogeneity. We conclude that the so far largely unexplored role of dance communication in pollen foraging requires further consideration as pollen is a crucial resource for colony development and health.}, language = {en} } @article{RedlichMartinWendeetal.2018, author = {Redlich, Sarah and Martin, Emily A. and Wende, Beate and Steffan-Dewenter, Ingolf}, title = {Landscape heterogeneity rather than crop diversity mediates bird diversity in agricultural landscapes}, series = {PLoS ONE}, volume = {13}, journal = {PLoS ONE}, number = {8}, doi = {10.1371/journal.pone.0200438}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177110}, pages = {e0200438}, year = {2018}, abstract = {Crop diversification has been proposed as farm management tool that could mitigate the externalities of conventional farming while reducing productivity-biodiversity trade-offs. Yet evidence for the acclaimed biodiversity benefits of landscape-level crop diversity is ambiguous. Effects may strongly depend on spatial scale and the level of landscape heterogeneity (e.g. overall habitat diversity). At the same time, contrasting within-taxon responses obscure benefits to specific functional groups (i.e. species with shared characteristics or requirements) if studied at the community level. The objectives of this study were to 1) disentangle the relative effects of crop diversity and landscape heterogeneity on avian species richness across five spatial scales ranging from 250 to 3000 m radii around focal winter wheat fields; and 2) assess whether functional groups (feeding guild, conservation status, habitat preference, nesting behaviour) determine the strength and direction of responses to crop diversity and landscape heterogeneity. In central Germany, 14 landscapes were selected along independent gradients of crop diversity (annual arable crops) and landscape heterogeneity. Bird species richness in each landscape was estimated using four point counts throughout the breeding season. We found no effects of landscape-level crop diversity on bird richness and functional groups. Instead, landscape heterogeneity was strongly associated with increased total bird richness across all spatial scales. In particular, insect-feeding and non-farmland birds were favoured in heterogeneous landscapes, as were species not classified as endangered or vulnerable on the regional Red List. Crop-nesting farmland birds, however, were less species-rich in these landscapes. Accordingly, crop diversification may be less suitable for conserving avian diversity and associated ecosystem services (e.g. biological pest control), although confounding interactions with management intensity need yet to be confirmed. In contrast, enhancement of landscape heterogeneity by increasing perennial habitat diversity, reducing field sizes and the amount of cropland has the potential to benefit overall bird richness. Specialist farmland birds, however, may require more targeted management approaches.}, language = {en} } @article{VansynghelOcampoArizaMaasetal.2022, author = {Vansynghel, Justine and Ocampo-Ariza, Carolina and Maas, Bea and Martin, Emily A. and Thomas, Evert and Hanf-Dressler, Tara and Schumacher, Nils-Christian and Ulloque-Samatelo, Carlos and Tscharntke, Teja and Steffan-Dewenter, Ingolf}, title = {Cacao flower visitation: Low pollen deposition, low fruit set and dominance of herbivores}, series = {Ecological Solutions and Evidence}, volume = {3}, journal = {Ecological Solutions and Evidence}, number = {2}, issn = {2688-8319}, doi = {10.1002/2688-8319.12140}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312722}, year = {2022}, abstract = {1. Pollination services of cacao are crucial for global chocolate production, yet remain critically understudied, particularly in regions of origin of the species. Notably, uncertainties remain concerning the identity of cacao pollinators, the influence of landscape (forest distance) and management (shade cover) on flower visitation and the role of pollen deposition in limiting fruit set. 2. Here, we aimed to improve understanding of cacao pollination by studying limiting factors of fruit set in Peru, part of the centre of origin of cacao. Flower visitors were sampled with sticky insect glue in 20 cacao agroforests in two biogeographically distinct regions of Peru, across gradients of shade cover and forest distance. Further, we assessed pollen quantities and compared fruit set between naturally and manually pollinated flowers. 3. The most abundant flower visitors were aphids, ants and thrips in the north and thrips, midges and parasitoid wasps in the south of Peru. We present some evidence of increasing visitation rates from medium to high shade (40\%-95\% canopy closure) in the dry north, and opposite patterns in the semi-humid south, during the wet season. 4. Natural pollination resulted in remarkably low fruit set rates (2\%), and very low pollen deposition. After hand pollination, fruit set more than tripled (7\%), but was still low. 5. The diversity and high relative abundances of herbivore flower visitors limit our ability to draw conclusions on the functional role of different flower visitors. The remarkably low fruit set of naturally and even hand pollinated flowers indicates that other unaddressed factors limit cacao fruit production. Such factors could be, amongst others, a lack of effective pollinators, genetic incompatibility or resource limitation. Revealing efficient pollinator species and other causes of low fruit set rates is therefore key to establish location-specific management strategies and develop high yielding native cacao agroforestry systems in regions of origin of cacao}, language = {en} } @article{KoenigKraussKelleretal.2022, author = {K{\"o}nig, Sebastian and Krauss, Jochen and Keller, Alexander and Bofinger, Lukas and Steffan-Dewenter, Ingolf}, title = {Phylogenetic relatedness of food plants reveals highest insect herbivore specialization at intermediate temperatures along a broad climatic gradient}, series = {Global Change Biology}, volume = {28}, journal = {Global Change Biology}, number = {13}, doi = {10.1111/gcb.16199}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276441}, pages = {4027 -- 4040}, year = {2022}, abstract = {The composition and richness of herbivore and plant assemblages change along climatic gradients, but knowledge about associated shifts in specialization is scarce and lacks controlling for the abundance and phylogeny of interaction partners. Thus, we aimed to test whether the specialization of phytophagous insects in insect-plant interaction networks decreases toward cold habitats as predicted by the 'altitude niche-breadth hypothesis' to forecast possible consequences of interaction rewiring under climate change. We used a non-invasive, standardized metabarcoding approach to reconstruct dietary relationships of Orthoptera species as a major insect herbivore taxon along a broad temperature gradient (~12°C) in Southern Germany. Based on Orthoptera surveys, feeding observations, collection of fecal pellets from >3,000 individuals of 54 species, and parallel vegetation surveys on 41 grassland sites, we quantified plant resource availability and its use by herbivores. Herbivore assemblages were richer in species and individuals at sites with high summer temperatures, while plant richness peaked at intermediate temperatures. Corresponding interaction networks were most specialized in warm habitats. Considering phylogenetic relationships of plant resources, however, the specialization pattern was not linear but peaked at intermediate temperatures, mediated by herbivores feeding on a narrow range of phylogenetically related resources. Our study provides empirical evidence of resource specialization of insect herbivores along a climatic gradient, demonstrating that resource phylogeny, availability, and temperature interactively shape the specialization of herbivore assemblages. Instead of low specialization levels only in cold, harsh habitats, our results suggest increased generalist feeding due to intraspecific changes and compositional differences at both ends of the microclimatic gradient. We conclude that this nonlinear change of phylogeny-based resource specialization questions predictions derived from the 'altitude-niche breadth hypothesis' and highlights the currently limited understanding of how plant-herbivore interactions will change under future climatic conditions.}, language = {en} } @article{GebertSteffanDewenterMorettoetal.2019, author = {Gebert, Friederike and Steffan-Dewenter, Ingolf and Moretto, Philippe and Peters, Marcell K.}, title = {Climate rather than dung resources predict dung beetle abundance and diversity along elevational and land use gradients on Mt. Kilimanjaro}, series = {Journal of Biogeography}, volume = {47}, journal = {Journal of Biogeography}, number = {2}, doi = {10.1111/jbi.13710}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204701}, pages = {371 -- 381}, year = {2019}, abstract = {Aim: While elevational gradients in species richness constitute some of the best depicted patterns in ecology, there is a large uncertainty concerning the role of food resource availability for the establishment of diversity gradients in insects. Here, we analysed the importance of climate, area, land use and food resources for determining diversity gradients of dung beetles along extensive elevation and land use gradients on Mt. Kilimanjaro, Tanzania. Location: Mt. Kilimanjaro, Tanzania. Taxon: Scarabaeidae (Coleoptera). Methods: Dung beetles were recorded with baited pitfall traps at 66 study plots along a 3.6 km elevational gradient. In order to quantify food resources for the dung beetle community in form of mammal defecation rates, we assessed mammalian diversity and biomass with camera traps. Using a multi-model inference framework and path analysis, we tested the direct and indirect links between climate, area, land use and mammal defecation rates on the species richness and abundance of dung beetles. Results: We found that the species richness of dung beetles declined exponentially with increasing elevation. Human land use diminished the species richness of functional groups exhibiting complex behaviour but did not have a significant influence on total species richness. Path analysis suggested that climate, in particular temperature and to a lesser degree precipitation, were the most important predictors of dung beetle species richness while mammal defecation rate was not supported as a predictor variable. Main conclusions: Along broad climatic gradients, dung beetle diversity is mainly limited by climatic factors rather than by food resources. Our study points to a predominant role of temperature-driven processes for the maintenance and origination of species diversity of ectothermic organisms, which will consequently be subject to ongoing climatic changes.}, language = {en} } @article{RequierPailletLarocheetal.2019, author = {Requier, Fabrice and Paillet, Yoan and Laroche, Fabienne and Rutschmann, Benjamin and Zhang, Jie and Lombardi, Fabio and Svoboda, Miroslav and Steffan-Dewenter, Ingolf}, title = {Contribution of European forests to safeguard wild honeybee populations}, series = {Conservation Letters}, volume = {13}, journal = {Conservation Letters}, number = {2}, doi = {10.1111/conl.12693}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204407}, pages = {e12693}, year = {2019}, abstract = {Abstract Recent studies reveal the use of tree cavities by wild honeybee colonies in European forests. This highlights the conservation potential of forests for a highly threatened component of the native entomofauna in Europe, but currently no estimate of potential wild honeybee population sizes exists. Here, we analyzed the tree cavity densities of 106 forest areas across Europe and inferred an expected population size of wild honeybees. Both forest and management types affected the density of tree cavities. Accordingly, we estimated that more than 80,000 wild honeybee colonies could be sustained in European forests. As expected, potential conservation hotspots were identified in unmanaged forests, and, surprisingly, also in other large forest areas across Europe. Our results contribute to the EU policy strategy to halt pollinator declines and reveal the potential of forest areas for the conservation of so far neglected wild honeybee populations in Europe.}, language = {en} } @article{BoetzlSchueleKraussetal.2020, author = {Boetzl, Fabian A. and Schuele, Maren and Krauss, Jochen and Steffan-Dewenter, Ingolf}, title = {Pest control potential of adjacent agri-environment schemes varies with crop type and is shaped by landscape context and within-field position}, series = {Journal of Applied Ecology}, volume = {57}, journal = {Journal of Applied Ecology}, number = {8}, doi = {10.1111/1365-2664.13653}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218265}, pages = {1482 -- 1493}, year = {2020}, abstract = {Increasing natural pest control in agricultural fields is an important aim of ecological intensification. Combined effects of landscape context and local placement of agri-environmental schemes (AES) on natural pest control and within-field distance functions of natural pest control agents have rarely been addressed but might affect the distribution of biocontrol providers. Importantly, it is currently unknown whether ecosystem services provided by adjacent AES are consistent for different crop types during crop rotation. In this study, we assessed whether crop rotation from oilseed rape to cereals altered within-field distance functions of ground-dwelling predators from adjacent agri-environmental fields along a gradient in landscape context. Additionally, we recorded crop pests, predation rates, parasitoids as well as crop yields on a total of 30 study sites. Distance functions varied between trophic levels: Carabid richness decreased while densities of carabid beetles, staphylinid beetles as well as crop yields increased towards the field centres. Distance functions of parasitoids and pests were modulated by the amount of semi-natural habitat in the surrounding landscape, while the effects of adjacent AES were limited. Distance decay functions found for ground-dwelling predators in oilseed rape in the previous year were not always present in cereals. Increasing distance to the field edge also increased effects of crop rotation on carabid beetle assemblages, indicating a source habitat function of field edges. Synthesis and applications. Distance functions of natural pest control are not universal and the effects of agri-environmental schemes (AES) in different adjacent crops during crop rotation vary and depend on ecological contrasts. A network of semi-natural habitats and spatially optimized AES habitats can benefit pest control in agricultural landscapes, but constraints as a result of crop type need to be addressed by annually targeted, spatially shifting agri-environment schemes for different crops.}, language = {en} } @article{VogelChungaSunetal.2021, author = {Vogel, Cassandra and Chunga, Timothy L. and Sun, Xiaoxuan and Poveda, Katja and Steffan-Dewenter, Ingolf}, title = {Higher bee abundance, but not pest abundance, in landscapes with more agriculture on a late-flowering legume crop in tropical smallholder farms}, series = {PeerJ}, volume = {9}, journal = {PeerJ}, doi = {10.7717/peerj.10732}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231491}, year = {2021}, abstract = {Background Landscape composition is known to affect both beneficial insect and pest communities on crop fields. Landscape composition therefore can impact ecosystem (dis)services provided by insects to crops. Though landscape effects on ecosystem service providers have been studied in large-scale agriculture in temperate regions, there is a lack of representation of tropical smallholder agriculture within this field of study, especially in sub-Sahara Africa. Legume crops can provide important food security and soil improvement benefits to vulnerable agriculturalists. However, legumes are dependent on pollinating insects, particularly bees (Hymenoptera: Apiformes) for production and are vulnerable to pests. We selected 10 pigeon pea (Fabaceae: Cajunus cajan (L.)) fields in Malawi with varying proportions of semi-natural habitat and agricultural area within a 1 km radius to study: (1) how the proportion of semi-natural habitat and agricultural area affects the abundance and richness of bees and abundance of florivorous blister beetles (Coleoptera: Melloidae), (2) if the proportion of flowers damaged and fruit set difference between open and bagged flowers are correlated with the proportion of semi-natural habitat or agricultural area and (3) if pigeon pea fruit set difference between open and bagged flowers in these landscapes was constrained by pest damage or improved by bee visitation. Methods We performed three, ten-minute, 15 m, transects per field to assess blister beetle abundance and bee abundance and richness. Bees were captured and identified to (morpho)species. We assessed the proportion of flowers damaged by beetles during the flowering period. We performed a pollinator and pest exclusion experiment on 15 plants per field to assess whether fruit set was pollinator limited or constrained by pests. Results In our study, bee abundance was higher in areas with proportionally more agricultural area surrounding the fields. This effect was mostly driven by an increase in honeybees. Bee richness and beetle abundances were not affected by landscape characteristics, nor was flower damage or fruit set difference between bagged and open flowers. We did not observe a positive effect of bee density or richness, nor a negative effect of florivory, on fruit set difference. Discussion In our study area, pigeon pea flowers relatively late—well into the dry season. This could explain why we observe higher densities of bees in areas dominated by agriculture rather than in areas with more semi-natural habitat where resources for bees during this time of the year are scarce. Therefore, late flowering legumes may be an important food resource for bees during a period of scarcity in the seasonal tropics. The differences in patterns between our study and those conducted in temperate regions highlight the need for landscape-scale studies in areas outside the temperate region.}, language = {en} } @article{DhillonDahmsKuebertFlocketal.2022, author = {Dhillon, Maninder Singh and Dahms, Thorsten and K{\"u}bert-Flock, Carina and Steffan-Dewenter, Ingolf and Zhang, Jie and Ullmann, Tobias}, title = {Spatiotemporal Fusion Modelling Using STARFM: Examples of Landsat 8 and Sentinel-2 NDVI in Bavaria}, series = {Remote Sensing}, volume = {14}, journal = {Remote Sensing}, number = {3}, issn = {2072-4292}, doi = {10.3390/rs14030677}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-323471}, year = {2022}, abstract = {The increasing availability and variety of global satellite products provide a new level of data with different spatial, temporal, and spectral resolutions; however, identifying the most suited resolution for a specific application consumes increasingly more time and computation effort. The region's cloud coverage additionally influences the choice of the best trade-off between spatial and temporal resolution, and different pixel sizes of remote sensing (RS) data may hinder the accurate monitoring of different land cover (LC) classes such as agriculture, forest, grassland, water, urban, and natural-seminatural. To investigate the importance of RS data for these LC classes, the present study fuses NDVIs of two high spatial resolution data (high pair) (Landsat (30 m, 16 days; L) and Sentinel-2 (10 m, 5-6 days; S), with four low spatial resolution data (low pair) (MOD13Q1 (250 m, 16 days), MCD43A4 (500 m, one day), MOD09GQ (250 m, one-day), and MOD09Q1 (250 m, eight day)) using the spatial and temporal adaptive reflectance fusion model (STARFM), which fills regions' cloud or shadow gaps without losing spatial information. These eight synthetic NDVI STARFM products (2: high pair multiply 4: low pair) offer a spatial resolution of 10 or 30 m and temporal resolution of 1, 8, or 16 days for the entire state of Bavaria (Germany) in 2019. Due to their higher revisit frequency and more cloud and shadow-free scenes (S = 13, L = 9), Sentinel-2 (overall R\(^2\) = 0.71, and RMSE = 0.11) synthetic NDVI products provide more accurate results than Landsat (overall R\(^2\) = 0.61, and RMSE = 0.13). Likewise, for the agriculture class, synthetic products obtained using Sentinel-2 resulted in higher accuracy than Landsat except for L-MOD13Q1 (R\(^2\) = 0.62, RMSE = 0.11), resulting in similar accuracy preciseness as S-MOD13Q1 (R\(^2\) = 0.68, RMSE = 0.13). Similarly, comparing L-MOD13Q1 (R\(^2\) = 0.60, RMSE = 0.05) and S-MOD13Q1 (R\(^2\) = 0.52, RMSE = 0.09) for the forest class, the former resulted in higher accuracy and precision than the latter. Conclusively, both L-MOD13Q1 and S-MOD13Q1 are suitable for agricultural and forest monitoring; however, the spatial resolution of 30 m and low storage capacity makes L-MOD13Q1 more prominent and faster than that of S-MOD13Q1 with the 10-m spatial resolution.}, language = {en} } @article{DhillonDahmsKuebertFlocketal.2023, author = {Dhillon, Maninder Singh and Dahms, Thorsten and K{\"u}bert-Flock, Carina and Liepa, Adomas and Rummler, Thomas and Arnault, Joel and Steffan-Dewenter, Ingolf and Ullmann, Tobias}, title = {Impact of STARFM on crop yield predictions: fusing MODIS with Landsat 5, 7, and 8 NDVIs in Bavaria Germany}, series = {Remote Sensing}, volume = {15}, journal = {Remote Sensing}, number = {6}, issn = {2072-4292}, doi = {10.3390/rs15061651}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311092}, year = {2023}, abstract = {Rapid and accurate yield estimates at both field and regional levels remain the goal of sustainable agriculture and food security. Hereby, the identification of consistent and reliable methodologies providing accurate yield predictions is one of the hot topics in agricultural research. This study investigated the relationship of spatiotemporal fusion modelling using STRAFM on crop yield prediction for winter wheat (WW) and oil-seed rape (OSR) using a semi-empirical light use efficiency (LUE) model for the Free State of Bavaria (70,550 km\(^2\)), Germany, from 2001 to 2019. A synthetic normalised difference vegetation index (NDVI) time series was generated and validated by fusing the high spatial resolution (30 m, 16 days) Landsat 5 Thematic Mapper (TM) (2001 to 2012), Landsat 7 Enhanced Thematic Mapper Plus (ETM+) (2012), and Landsat 8 Operational Land Imager (OLI) (2013 to 2019) with the coarse resolution of MOD13Q1 (250 m, 16 days) from 2001 to 2019. Except for some temporal periods (i.e., 2001, 2002, and 2012), the study obtained an R\(^2\) of more than 0.65 and a RMSE of less than 0.11, which proves that the Landsat 8 OLI fused products are of higher accuracy than the Landsat 5 TM products. Moreover, the accuracies of the NDVI fusion data have been found to correlate with the total number of available Landsat scenes every year (N), with a correlation coefficient (R) of +0.83 (between R\(^2\) of yearly synthetic NDVIs and N) and -0.84 (between RMSEs and N). For crop yield prediction, the synthetic NDVI time series and climate elements (such as minimum temperature, maximum temperature, relative humidity, evaporation, transpiration, and solar radiation) are inputted to the LUE model, resulting in an average R\(^2\) of 0.75 (WW) and 0.73 (OSR), and RMSEs of 4.33 dt/ha and 2.19 dt/ha. The yield prediction results prove the consistency and stability of the LUE model for yield estimation. Using the LUE model, accurate crop yield predictions were obtained for WW (R\(^2\) = 0.88) and OSR (R\(^2\) = 0.74). Lastly, the study observed a high positive correlation of R = 0.81 and R = 0.77 between the yearly R\(^2\) of synthetic accuracy and modelled yield accuracy for WW and OSR, respectively.}, language = {en} } @article{DhillonKuebertFlockDahmsetal.2023, author = {Dhillon, Maninder Singh and K{\"u}bert-Flock, Carina and Dahms, Thorsten and Rummler, Thomas and Arnault, Joel and Steffan-Dewenter, Ingolf and Ullmann, Tobias}, title = {Evaluation of MODIS, Landsat 8 and Sentinel-2 data for accurate crop yield predictions: a case study using STARFM NDVI in Bavaria, Germany}, series = {Remote Sensing}, volume = {15}, journal = {Remote Sensing}, number = {7}, issn = {2072-4292}, doi = {10.3390/rs15071830}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311132}, year = {2023}, abstract = {The increasing availability and variety of global satellite products and the rapid development of new algorithms has provided great potential to generate a new level of data with different spatial, temporal, and spectral resolutions. However, the ability of these synthetic spatiotemporal datasets to accurately map and monitor our planet on a field or regional scale remains underexplored. This study aimed to support future research efforts in estimating crop yields by identifying the optimal spatial (10 m, 30 m, or 250 m) and temporal (8 or 16 days) resolutions on a regional scale. The current study explored and discussed the suitability of four different synthetic (Landsat (L)-MOD13Q1 (30 m, 8 and 16 days) and Sentinel-2 (S)-MOD13Q1 (10 m, 8 and 16 days)) and two real (MOD13Q1 (250 m, 8 and 16 days)) NDVI products combined separately to two widely used crop growth models (CGMs) (World Food Studies (WOFOST), and the semi-empiric Light Use Efficiency approach (LUE)) for winter wheat (WW) and oil seed rape (OSR) yield forecasts in Bavaria (70,550 km\(^2\)) for the year 2019. For WW and OSR, the synthetic products' high spatial and temporal resolution resulted in higher yield accuracies using LUE and WOFOST. The observations of high temporal resolution (8-day) products of both S-MOD13Q1 and L-MOD13Q1 played a significant role in accurately measuring the yield of WW and OSR. For example, L- and S-MOD13Q1 resulted in an R\(^2\) = 0.82 and 0.85, RMSE = 5.46 and 5.01 dt/ha for WW, R\(^2\) = 0.89 and 0.82, and RMSE = 2.23 and 2.11 dt/ha for OSR using the LUE model, respectively. Similarly, for the 8- and 16-day products, the simple LUE model (R\(^2\) = 0.77 and relative RMSE (RRMSE) = 8.17\%) required fewer input parameters to simulate crop yield and was highly accurate, reliable, and more precise than the complex WOFOST model (R\(^2\) = 0.66 and RRMSE = 11.35\%) with higher input parameters. Conclusively, both S-MOD13Q1 and L-MOD13Q1, in combination with LUE, were more prominent for predicting crop yields on a regional scale than the 16-day products; however, L-MOD13Q1 was advantageous for generating and exploring the long-term yield time series due to the availability of Landsat data since 1982, with a maximum resolution of 30 m. In addition, this study recommended the further use of its findings for implementing and validating the long-term crop yield time series in different regions of the world.}, language = {en} } @article{EnglmeierMitesserBenbowetal.2023, author = {Englmeier, Jana and Mitesser, Oliver and Benbow, M. Eric and Hothorn, Torsten and von Hoermann, Christian and Benjamin, Caryl and Fricke, Ute and Ganuza, Cristina and Haensel, Maria and Redlich, Sarah and Riebl, Rebekka and Rojas Botero, Sandra and Rummler, Thomas and Steffan-Dewenter, Ingolf and Stengel, Elisa and Tobisch, Cynthia and Uhler, Johannes and Uphus, Lars and Zhang, Jie and M{\"u}ller, J{\"o}rg}, title = {Diverse effects of climate, land use, and insects on dung and carrion decomposition}, series = {Ecosystems}, volume = {26}, journal = {Ecosystems}, number = {2}, issn = {1432-9840}, doi = {10.1007/s10021-022-00764-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-325064}, pages = {397-411}, year = {2023}, abstract = {Land-use intensification and climate change threaten ecosystem functions. A fundamental, yet often overlooked, function is decomposition of necromass. The direct and indirect anthropogenic effects on decomposition, however, are poorly understood. We measured decomposition of two contrasting types of necromass, rat carrion and bison dung, on 179 study sites in Central Europe across an elevational climate gradient of 168-1122 m a.s.l. and within both local and regional land uses. Local land-use types included forest, grassland, arable fields, and settlements and were embedded in three regional land-use types (near-natural, agricultural, and urban). The effects of insects on decomposition were quantified by experimental exclusion, while controlling for removal by vertebrates. We used generalized additive mixed models to evaluate dung weight loss and carrion decay rate along elevation and across regional and local land-use types. We observed a unimodal relationship of dung decomposition with elevation, where greatest weight loss occurred between 600 and 700 m, but no effects of local temperature, land use, or insects. In contrast to dung, carrion decomposition was continuously faster with both increasing elevation and local temperature. Carrion reached the final decomposition stage six days earlier when insect access was allowed, and this did not depend on land-use effect. Our experiment identified different major drivers of decomposition on each necromass form. The results show that dung and carrion decomposition are rather robust to local and regional land use, but future climate change and decline of insects could alter decomposition processes and the self-regulation of ecosystems.}, language = {en} } @article{FrickeRedlichZhangetal.2022, author = {Fricke, Ute and Redlich, Sarah and Zhang, Jie and Tobisch, Cynthia and Rojas-Botero, Sandra and Benjamin, Caryl S. and Englmeier, Jana and Ganuza, Cristina and Riebl, Rebekka and Uhler, Johannes and Uphus, Lars and Ewald, J{\"o}rg and Kollmann, Johannes and Steffan-Dewenter, Ingolf}, title = {Plant richness, land use and temperature differently shape invertebrate leaf-chewing herbivory on plant functional groups}, series = {Oecologia}, volume = {199}, journal = {Oecologia}, number = {2}, doi = {10.1007/s00442-022-05199-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-325079}, pages = {407-417}, year = {2022}, abstract = {Higher temperatures can increase metabolic rates and carbon demands of invertebrate herbivores, which may shift leaf-chewing herbivory among plant functional groups differing in C:N (carbon:nitrogen) ratios. Biotic factors influencing herbivore species richness may modulate these temperature effects. Yet, systematic studies comparing leaf-chewing herbivory among plant functional groups in different habitats and landscapes along temperature gradients are lacking. This study was conducted on 80 plots covering large gradients of temperature, plant richness and land use in Bavaria, Germany. We investigated proportional leaf area loss by chewing invertebrates ('herbivory') in three plant functional groups on open herbaceous vegetation. As potential drivers, we considered local mean temperature (range 8.4-18.8 °C), multi-annual mean temperature (range 6.5-10.0 °C), local plant richness (species and family level, ranges 10-51 species, 5-25 families), adjacent habitat type (forest, grassland, arable field, settlement), proportion of grassland and landscape diversity (0.2-3 km scale). We observed differential responses of leaf-chewing herbivory among plant functional groups in response to plant richness (family level only) and habitat type, but not to grassland proportion, landscape diversity and temperature—except for multi-annual mean temperature influencing herbivory on grassland plots. Three-way interactions of plant functional group, temperature and predictors of plant richness or land use did not substantially impact herbivory. We conclude that abiotic and biotic factors can assert different effects on leaf-chewing herbivory among plant functional groups. At present, effects of plant richness and habitat type outweigh effects of temperature and landscape-scale land use on herbivory among legumes, forbs and grasses.}, language = {en} }