TY  - JOUR
A1  - Bae, Soyeon
A1  - Müller, Jörg
A1  - Förster, Bernhard
A1  - Hilmers, Torben
A1  - Hochrein, Sophia
A1  - Jacobs, Martin
A1  - Leroy, Benjamin M. L.
A1  - Pretzsch, Hans
A1  - Weisser, Wolfgang W.
A1  - Mitesser, Oliver
T1  - Tracking the temporal dynamics of insect defoliation by high‐resolution radar satellite data
JF  - Methods in Ecology and Evolution
N2  - Quantifying tree defoliation by insects over large areas is a major challenge in forest management, but it is essential in ecosystem assessments of disturbance and resistance against herbivory. However, the trajectory from leaf-flush to insect defoliation to refoliation in broadleaf trees is highly variable. Its tracking requires high temporal- and spatial-resolution data, particularly in fragmented forests.
In a unique replicated field experiment manipulating gypsy moth Lymantria dispar densities in mixed-oak forests, we examined the utility of publicly accessible satellite-borne radar (Sentinel-1) to track the fine-scale temporal trajectory of defoliation. The ratio of backscatter intensity between two polarizations from radar data of the growing season constituted a canopy development index (CDI) and a normalized CDI (NCDI), which were validated by optical (Sentinel-2) and terrestrial laser scanning (TLS) data as well by intensive caterpillar sampling from canopy fogging.
The CDI and NCDI strongly correlated with optical and TLS data (Spearman's ρ = 0.79 and 0.84, respectively). The ΔNCDII\(_{Defoliation(A−C)}\) significantly explained caterpillar abundance (R\(^{2}\) = 0.52). The NCDI at critical timesteps and ΔNCDI related to defoliation and refoliation well discriminated between heavily and lightly defoliated forests.
We demonstrate that the high spatial and temporal resolution and the cloud independence of Sentinel-1 radar potentially enable spatially unrestricted measurements of the highly dynamic canopy herbivory. This can help monitor insect pests, improve the prediction of outbreaks and facilitate the monitoring of forest disturbance, one of the high priority Essential Biodiversity Variables, in the near future.
KW  - Sentinel-1
KW  - canopy herbivory
KW  - defoliation severity
KW  - gypsy moth
KW  - insect disturbance
KW  - intra-annual time-series
KW  - Lymantria dispar
KW  - remote sensing
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258222
VL  - 13
IS  - 1
ER  - 
TY  - JOUR
A1  - Degen, Tobias
A1  - Hovestadt, Thomas
A1  - Mitesser, Oliver
A1  - Hölker, Franz
T1  - Altered sex-specific mortality and female mating success: ecological effects and evolutionary responses
JF  - Ecosphere
N2  - Theory predicts that males and females should often join the mating pool at different times (sexual dimorphism in timing of emergence [SDT]) as the degree of SDT affects female mating success. We utilize an analytical model to explore (1) how important SDT is for female mating success, (2) how mating success might change if either sex's mortality (abruptly) increases, and (3) to what degree evolutionary responses in SDT may be able to mitigate the consequences of such mortality increase. Increasing male pre‐mating mortality has a non‐linear effect on the fraction of females mated: The effect is initially weak, but at some critical level a further increase in male mortality has a stronger effect than a similar increase in female mortality. Such a change is expected to impose selection for reduced SDT. Increasing mortality during the mating season has always a stronger effect on female mating success if the mortality affects the sex that emerges first. This bias results from the fact that enhancing mortality of the earlier emerging sex reduces female–male encounter rates. However, an evolutionary response in SDT may effectively mitigate such consequences. Further, if considered independently for females and males, the predicted evolutionary response in SDT could be quite dissimilar. The difference between female and male evolutionary response in SDT leads to marked differences in the fraction of fertilized females under certain conditions. Our model may provide general guidelines for improving harvesting of populations, conservation management of rare species under altered environmental conditions, or maintaining long‐term efficiency of pest‐control measures.
KW  - evolutionary response
KW  - sexual dimorphism in timing
KW  - sex-specific mortality
KW  - reproductive asynchrony
KW  - mating success
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170953
VL  - 8
IS  - 5
ER  - 
TY  - JOUR
A1  - Degen, Tobias
A1  - Hovestadt, Thomas
A1  - Mitesser, Oliver
A1  - Hölker, Franz
T1  - High female survival promotes evolution of protogyny and xexual conflict
JF  - PLoS ONE
N2  - Existing models explaining the evolution of sexual dimorphism in the timing of emergence (SDT) in Lepidoptera assume equal mortality rates for males and females. The limiting assumption of equal mortality rates has the consequence that these models are only able to explain the evolution of emergence of males before females, i.e. protandry-the more common temporal sequence of emergence in Lepidoptera. The models fail, however, in providing adaptive explanations for the evolution of protogyny, where females emerge before males, but protogyny is not rare in insects. The assumption of equal mortality rates seems too restrictive for many insects, such as butterflies. To investigate the influence of unequal mortality rates on the evolution of SDT, we present a generalised version of a previously published model where we relax this assumption. We find that longer life-expectancy of females compared to males can indeed favour the evolution of protogyny as a fitness enhancing strategy. Moreover, the encounter rate between females and males and the sex-ratio are two important factors that also influence the evolution of optimal SDT. If considered independently for females and males the predicted strategies can be shown to be evolutionarily stable (ESS). Under the assumption of equal mortality rates the difference between the females' and males' ESS remains typically very small. However, female and male ESS may be quite dissimilar if mortality rates are different. This creates the potential for an 'evolutionary conflict' between females and males. Bagworm moths (Lepidoptera: Psychidae) provide an exemplary case where life-history attributes are such that protogyny should indeed be the optimal emergence strategy from the males' and females' perspectives: (i) Female longevity is considerably larger than that of males, (ii) encounter rates between females and males are presumably low, and (iii) females mate only once. Protogyny is indeed the general mating strategy found in the bagworm family.
KW  - mortality rates
KW  - bagworms Lepidoptera
KW  - size dimorphism
KW  - mating success
KW  - life span
KW  - armyworm Lepidoptera
KW  - adaptive growth
KW  - males emerge
KW  - protandry
KW  - butterflies
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143586
VL  - 10
IS  - 3
ER  - 
TY  - JOUR
A1  - Englmeier, Jana
A1  - Mitesser, Oliver
A1  - Benbow, M. Eric
A1  - Hothorn, Torsten
A1  - von Hoermann, Christian
A1  - Benjamin, Caryl
A1  - Fricke, Ute
A1  - Ganuza, Cristina
A1  - Haensel, Maria
A1  - Redlich, Sarah
A1  - Riebl, Rebekka
A1  - Rojas Botero, Sandra
A1  - Rummler, Thomas
A1  - Steffan-Dewenter, Ingolf
A1  - Stengel, Elisa
A1  - Tobisch, Cynthia
A1  - Uhler, Johannes
A1  - Uphus, Lars
A1  - Zhang, Jie
A1  - Müller, Jörg
T1  - Diverse effects of climate, land use, and insects on dung and carrion decomposition
JF  - Ecosystems
N2  - 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.
KW  - decay
KW  - ecosystem function
KW  - global change
KW  - land-use intensification
KW  - necrobiome
KW  - urbanization
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-325064
SN  - 1432-9840
VL  - 26
IS  - 2
ER  - 
TY  - JOUR
A1  - Englmeier, Jana
A1  - von Hoermann, Christian
A1  - Rieker, Daniel
A1  - Benbow, Marc Eric
A1  - Benjamin, Caryl
A1  - Fricke, Ute
A1  - Ganuza, Cristina
A1  - Haensel, Maria
A1  - Lackner, Tomáš
A1  - Mitesser, Oliver
A1  - Redlich, Sarah
A1  - Riebl, Rebekka
A1  - Rojas-Botero, Sandra
A1  - Rummler, Thomas
A1  - Salamon, Jörg-Alfred
A1  - Sommer, David
A1  - Steffan-Dewenter, Ingolf
A1  - Tobisch, Cynthia
A1  - Uhler, Johannes
A1  - Uphus, Lars
A1  - Zhang, Jie
A1  - Müller, Jörg
T1  - Dung-visiting beetle diversity is mainly affected by land use, while community specialization is driven by climate
JF  - Ecology and Evolution
N2  - 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.
KW  - coleoptera
KW  - coprophagous beetles
KW  - decomposition
KW  - global change
KW  - hill numbers
KW  - network analysis
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312846
SN  - 2045-7758
VL  - 12
IS  - 10
ER  - 
TY  - JOUR
A1  - Frank, Erik Thomas
A1  - Schmitt, Thomas
A1  - Hovestadt, Thomas
A1  - Mitesser, Oliver
A1  - Stiegler, Jonas
A1  - Linsenmair, Karl Eduard
T1  - Saving the injured: Rescue behavior in the termite-hunting ant Megaponera analis
JF  - Science Advances
N2  - Predators of highly defensive prey likely develop cost-reducing adaptations. The ant Megaponera analis is a specialized termite predator, solely raiding termites of the subfamily Macrotermitinae (in this study, mostly colonies of Pseudocanthotermes sp.) at their foraging sites. The evolutionary arms race between termites and ants led to various defensive mechanisms in termites (for example, a caste specialized in fighting predators). Because M. analis incurs high injury/mortality risks when preying on termites, some risk-mitigating adaptations seem likely to have evolved. We show that a unique rescue behavior in M. analis, consisting of injured nestmates being carried back to the nest, reduces combat mortality. After a fight, injured ants are carried back by their nestmates; these ants have usually lost an extremity or have termites clinging to them and are able to recover within the nest. Injured ants that are forced experimentally to return without help, die in 32% of the cases. Behavioral experiments show that two compounds, dimethyl disulfide and dimethyl trisulfide, present in the mandibular gland reservoirs, trigger the rescue behavior. A model accounting for this rescue behavior identifies the drivers favoring its evolution and estimates that rescuing enables maintenance of a 28.7% larger colony size. Our results are the first to explore experimentally the adaptive value of this form of rescue behavior focused on injured nestmates in social insects and help us to identify evolutionary drivers responsible for this type of behavior to evolve in animals.
KW  - Megaponera analis
KW  - rescue behavior
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-157933
VL  - 3
IS  - 4
ER  - 
TY  - JOUR
A1  - Heisswolf, Annette
A1  - Ulmann, Sandra
A1  - Obermaier, Elisabeth
A1  - Mitesser, Oliver
A1  - Poethke, Hans J.
T1  - Host plant finding in the specialised leaf beetle Cassida canaliculata: an analysis of small-scale movement behaviour
N2  - 1. Host plant finding in walking herbivorous beetles is still poorly understood. Analysis of small-scale movement patterns under semi-natural conditions can be a useful tool to detect behavioural responses towards host plant cues. 2. In this study, the small-scale movement behaviour of the monophagous leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) was studied in a semi-natural arena (r = 1 m). In three different settings, a host (Salvia pratensis L., Lamiales: Lamiaceae), a non-host (Rumex conglomeratus Murr., Caryophyllales: Polygonaceae), or no plant was presented in the centre of the arena. 3. The beetles showed no differences in the absolute movement variables, straightness and mean walking speed, between the three settings. However, the relative movement variables, mean distance to the centre and mean angular deviation from walking straight to the centre, were significantly smaller when a host plant was offered. Likewise, the angular deviation from walking straight to the centre tended to decline with decreasing distance from the centre. Finally, significantly more beetles were found on the host than on the non-host at the end of all the trials. 4. It is concluded that C. canaliculata is able to recognise its host plant from a distance. Whether olfactory or visual cues (or a combination of both) are used to find the host plant remains to be elucidated by further studies.
KW  - Käfer
KW  - Blattkäfer
KW  - Ampfer
KW  - Wiesensalbei
KW  - Arena experiment
KW  - Coleoptera
KW  - Chrysomelidae
KW  - olfaction
KW  - Rumex
KW  - Salvia pratensis
KW  - vision
KW  - walking
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-49485
ER  - 
TY  - JOUR
A1  - Horn, Melanie
A1  - Mitesser, Oliver
A1  - Hovestadt, Thomas
A1  - Yoshii, Taishi
A1  - Rieger, Dirk
A1  - Helfrich-Förster, Charlotte
T1  - The circadian clock improves fitness in the fruit fly, Drosophila melanogaster
JF  - Frontiers in Physiology
N2  - It is assumed that a properly timed circadian clock enhances fitness, but only few studies have truly demonstrated this in animals. We raised each of the three classical Drosophila period mutants for >50 generations in the laboratory in competition with wildtype flies. The populations were either kept under a conventional 24-h day or under cycles that matched the mutant’s natural cycle, i.e., a 19-h day in the case of pers mutants and a 29-h day for perl mutants. The arrhythmic per0 mutants were grown together with wildtype flies under constant light that renders wildtype flies similar arrhythmic as the mutants. In addition, the mutants had to compete with wildtype flies for two summers in two consecutive years under outdoor conditions. We found that wildtype flies quickly outcompeted the mutant flies under the 24-h laboratory day and under outdoor conditions, but perl mutants persisted and even outnumbered the wildtype flies under the 29-h day in the laboratory. In contrast, pers and per0 mutants did not win against wildtype flies under the 19-h day and constant light, respectively. Our results demonstrate that wildtype flies have a clear fitness advantage in terms of fertility and offspring survival over the period mutants and – as revealed for perl mutants – this advantage appears maximal when the endogenous period resonates with the period of the environment. However, the experiments indicate that perl and pers persist at low frequencies in the population even under the 24-h day. This may be a consequence of a certain mating preference of wildtype and heterozygous females for mutant males and time differences in activity patterns between wildtype and mutants.
KW  - competition
KW  - mutants
KW  - resonance theory
KW  - mating preference
KW  - fertility
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-195738
SN  - 1664-042X
VL  - 10
IS  - 1374
ER  - 
TY  - JOUR
A1  - Hovestadt, Thomas
A1  - Mitesser, Oliver
A1  - Elmes, Graham
A1  - Thomas, Jeremy A.
A1  - Hochberg, Michael E.
T1  - An Evolutionarily Stable Strategy model for the evolution of dimorphic development in the butterfly Maculinea rebeli, a social parasite of Myrmica Ant Colonies
N2  - Caterpillars of the butterfly Maculinea rebeli develop as parasites inside ant colonies. In intensively studied French populations, about 25% of caterpillars mature within 1 year (fast-developing larvae [FDL]) and the others after 2 years (slow-developing larvae [SDL]); all available evidence indicates that this ratio is under the control of egg-laying females. We present an analytical model to predict the evolutionarily stable fraction of FDL (pESS). The model accounts for added winter mortality of SDL, general and kin competition among caterpillars, a competitive advantage of SDL over newly entering FDL (priority effect), and the avoidance of renewed infection of ant nests by butterflies in the coming season (segregation). We come to the following conclusions: (1) all factors listed above can promote the evolution of delayed development; (2) kin competition and segregation stabilize pESS near 0.5; and (3) a priority effect is the only mechanism potentially selecting for. However, given the empirical data, pESS is predicted to fall closer to 0.5 than to the 0.25 that has been observed. In this particular system, bet hedging cannot explain why more than 50% of larvae postpone growth. Presumably, other fitness benefits for SDL, for example, higher fertility or longevity, also contribute to the evolution of delayed development. The model presented here may be of general applicability for systems where maturing individuals compete in small subgroups.
KW  - delayed development
KW  - growth dimorphism
KW  - evolutionarily stable strategy (ESS)
KW  - ant-butterfly interaction
KW  - social parasitism
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48165
ER  - 
TY  - JOUR
A1  - Hovestadt, Thomas
A1  - Thomas, Jeremy A.
A1  - Mitesser, Oliver
A1  - Schönrogge, Karsten
T1  - Multiple host use and the dynamics of host-switching in host-parasite systems
JF  - Insect Conservation and Diversity
N2  - The link between multi‐host use and host switching in host–parasite interactions is a continuing area of debate. Lycaenid butterflies in the genus Maculinea, for example, exploit societies of different Myrmica ant species across their ranges, but there is only rare evidence that they simultaneously utilise multiple hosts at a local site, even where alternative hosts are present.
We present a simple population‐genetic model accounting for the proportion of two alternative hosts and the fitness of parasite genotypes on each host. In agreement with standard models, we conclude that simultaneous host use is possible whenever fitness of heterozygotes on alternative hosts is not too low.
We specifically focus on host‐shifting dynamics when the frequency of hosts changes. We find that (i) host shifting may proceed so rapidly that multiple host use is unlikely to be observed, (ii) back and forth transition in host use can exhibit a hysteresis loop, (iii) the parasites' host use may not be proportional to local host frequencies and be restricted to the rarer host under some conditions, and (iv) that a substantial decline in parasite abundance may typically precede a shift in host use.
We conclude that focusing not just on possible equilibrium conditions but also considering the dynamics of host shifting in non‐equilibrium situations may provide added insights into host–parasite systems.
KW  - Host-parasite interaction
KW  - Maculinea butterfly
KW  - Myrmica ant non-equilibrium dynamics
KW  - population genetics
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204747
VL  - 12
IS  - 6
ER  -