@article{LeonhardtSchmittBluethgen2011, author = {Leonhardt, Sara D. and Schmitt, Thomas and Bl{\"u}thgen, Nico}, title = {Tree Resin Composition, Collection Behavior and Selective Filters Shape Chemical Profiles of Tropical Bees (Apidae: Meliponini)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69035}, year = {2011}, abstract = {The diversity of species is striking, but can be far exceeded by the chemical diversity of compounds collected, produced or used by them. Here, we relate the specificity of plant-consumer interactions to chemical diversity applying a comparative network analysis to both levels. Chemical diversity was explored for interactions between tropical stingless bees and plant resins, which bees collect for nest construction and to deter predators and microbes. Resins also function as an environmental source for terpenes that serve as appeasement allomones and protection against predators when accumulated on the bees' body surfaces. To unravel the origin of the bees' complex chemical profiles, we investigated resin collection and the processing of resin-derived terpenes. We therefore analyzed chemical networks of tree resins, foraging networks of resin collecting bees, and their acquired chemical networks. We revealed that 113 terpenes in nests of six bee species and 83 on their body surfaces comprised a subset of the 1,117 compounds found in resins from seven tree species. Sesquiterpenes were the most variable class of terpenes. Albeit widely present in tree resins, they were only found on the body surface of some species, but entirely lacking in others. Moreover, whereas the nest profile of Tetragonula melanocephala contained sesquiterpenes, its surface profile did not. Stingless bees showed a generalized collecting behavior among resin sources, and only a hitherto undescribed species-specific ''filtering'' of resin-derived terpenes can explain the variation in chemical profiles of nests and body surfaces fromdifferent species. The tight relationship between bees and tree resins of a large variety of species elucidates why the bees' surfaces contain a much higher chemodiversity than other hymenopterans.}, subject = {Stachellose Biene}, language = {en} } @article{KerkauSchmittLandgrafSchimpletal.1989, author = {Kerkau, Thomas and Schmitt-Landgraf, Renate and Schimpl, Anneliese and Wecker, Eberhard}, title = {Downregulation of HLA Class I Antigensin HIV-1-Infected Cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47172}, year = {1989}, abstract = {By means of indirect immunofluorescence analysis we investigated the effect of HIV -1 infection on HLA class I surface antigens. We report here that in CD4\(^+\) HeLa cells, in H9 cells, and in peripheral T Iymphocytes HLA class I antigens are down regulated following infection with HIV -1. The downregulation is effected at a posttranscriptional level since the amounts of HLA class I specific mRNA are similar in infected and uninfected cells. This phenomenon is not only correlated with the state of infection, that is, the presence of P24 of HIV-l in the cells, but also depends on the time of infection. Upon HLA class I downregulation by HIV infection, the specific lysis of peripheral blood cells by allogeneic CTL is reduced.}, language = {en} } @article{DrescherBluethgenSchmittetal.2010, author = {Drescher, Jochen and Bluethgen, Nico and Schmitt, Thomas and Buehler, Jana and Feldhaar, Heike}, title = {Societies Drifting Apart? Behavioural, Genetic and Chemical Differentiation between Supercolonies in the Yellow Crazy Ant Anoplolepis gracilipes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68573}, year = {2010}, abstract = {Background: In populations of most social insects, gene flow is maintained through mating between reproductive individuals from different colonies in periodic nuptial flights followed by dispersal of the fertilized foundresses. Some ant species, however, form large polygynous supercolonies, in which mating takes place within the maternal nest (intranidal mating) and fertilized queens disperse within or along the boundary of the supercolony, leading to supercolony growth (colony budding). As a consequence, gene flow is largely confined within supercolonies. Over time, such supercolonies may diverge genetically and, thus, also in recognition cues (cuticular hydrocarbons, CHC's) by a combination of genetic drift and accumulation of colony-specific, neutral mutations. Methodology/Principal Findings: We tested this hypothesis for six supercolonies of the invasive ant Anoplolepis gracilipes in north-east Borneo. Within supercolonies, workers from different nests tolerated each other, were closely related and showed highly similar CHC profiles. Between supercolonies, aggression ranged from tolerance to mortal encounters and was negatively correlated with relatedness and CHC profile similarity. Supercolonies were genetically and chemically distinct, with mutually aggressive supercolony pairs sharing only 33.1\%617.5\% (mean 6 SD) of their alleles across six microsatellite loci and 73.8\%611.6\% of the compounds in their CHC profile. Moreover, the proportion of alleles that differed between supercolony pairs was positively correlated to the proportion of qualitatively different CHC compounds. These qualitatively differing CHC compounds were found across various substance classes including alkanes, alkenes and mono-, di- and trimethyl-branched alkanes. Conclusions: We conclude that positive feedback between genetic, chemical and behavioural traits may further enhance supercolony differentiation through genetic drift and neutral evolution, and may drive colonies towards different evolutionary pathways, possibly including speciation.}, subject = {Ameisen}, language = {en} } @article{MenzelBluethgenTolaschetal.2013, author = {Menzel, Florian and Bl{\"u}thgen, Nico and Tolasch, Till and Conrad, J{\"u}rgen and Beifuss, Uwe and Beuerle, Till and Schmitt, Thomas}, title = {Crematoenones - a novel substance class exhibited by ants functions as appeasement signal}, series = {Frontiers in Zoology}, volume = {10}, journal = {Frontiers in Zoology}, number = {32}, issn = {1742-9994}, doi = {10.1186/1742-9994-10-32}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122595}, year = {2013}, abstract = {Background: Parasitic, commensalistic, and mutualistic guests in social insect colonies often circumvent their hosts' nestmate recognition system to be accepted. These tolerance strategies include chemical mimicry and chemical insignificance. While tolerance strategies have been studied intensively in social parasites, little is known about these mechanisms in non-parasitic interactions. Here, we describe a strategy used in a parabiotic association, i.e. two mutualistic ant species that regularly share a common nest although they have overlapping food niches. One of them, Crematogaster modiglianii, produces an array of cuticular compounds which represent a substance class undescribed in nature so far. They occur in high abundances, which suggests an important function in the ant's association with its partner Camponotus rufifemur. Results: We elucidated the structure of one of the main compounds from cuticular extracts using gas chromatography, mass spectrometry, chemical derivatizations and nuclear magnetic resonance spectroscopy (NMR). The compound consists of two fused six-membered rings with two alkyl groups, one of which carries a keto functionality. To our knowledge, this is the first report on the identification of this substance class in nature. We suggest naming the compound crematoenone. In behavioural assays, crematoenones reduced interspecific aggression. Camponotus showed less aggression to allospecific cuticular hydrocarbons when combined with crematoenones. Thus, they function as appeasement substances. However, although the crematoenone composition was highly colony-specific, interspecific recognition was mediated by cuticular hydrocarbons, and not by crematoenones. Conclusions: Crematenones enable Crematogaster to evade Camponotus aggression, and thus reduce potential costs from competition with Camponotus. Hence, they seem to be a key factor in the parabiosis, and help Crematogaster to gain a net benefit from the association and thus maintain a mutualistic association over evolutionary time. To our knowledge, putative appeasement substances have been reported only once so far, and never between non-parasitic species. Since most organisms associated with social insects need to overcome their nestmate recognition system, we hypothesize that appeasement substances might play an important role in the evolution and maintenance of other mutualistic associations as well, by allowing organisms to reduce costs from antagonistic behaviour of other species.}, language = {en} } @article{RoedelBredeHirschfeldetal.2013, author = {R{\"o}del, Mark-Oliver and Brede, Christian and Hirschfeld, Mareike and Schmitt, Thomas and Favreau, Philippe and St{\"o}cklin, Reto and Wunder, Cora and Mebs, Dietrich}, title = {Chemical Camouflage - A Frog's Strategy to Co-Exist with Aggressive Ants}, series = {PLOS ONE}, volume = {8}, journal = {PLOS ONE}, number = {12}, issn = {1932-6203}, doi = {10.1371/journal.pone.0081950}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128181}, pages = {e81950}, year = {2013}, abstract = {Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus). The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.}, language = {en} } @article{StrubeBlossBrownSpaetheetal.2015, author = {Strube-Bloss, Martin F. and Brown, Austin and Spaethe, Johannes and Schmitt, Thomas and R{\"o}ssler, Wolfgang}, title = {Extracting the Behaviorally Relevant Stimulus: Unique Neural Representation of Farnesol, a Component of the Recruitment Pheromone of Bombus terrestris}, series = {PLoS One}, volume = {10}, journal = {PLoS One}, number = {9}, doi = {10.1371/journal.pone.0137413}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125875}, pages = {e0137413}, year = {2015}, abstract = {To trigger innate behavior, sensory neural networks are pre-tuned to extract biologically relevant stimuli. Many male-female or insect-plant interactions depend on this phenomenon. Especially communication among individuals within social groups depends on innate behaviors. One example is the efficient recruitment of nest mates by successful bumblebee foragers. Returning foragers release a recruitment pheromone in the nest while they perform a 'dance' behavior to activate unemployed nest mates. A major component of this pheromone is the sesquiterpenoid farnesol. How farnesol is processed and perceived by the olfactory system, has not yet been identified. It is much likely that processing farnesol involves an innate mechanism for the extraction of relevant information to trigger a fast and reliable behavioral response. To test this hypothesis, we used population response analyses of 100 antennal lobe (AL) neurons recorded in alive bumblebee workers under repeated stimulation with four behaviorally different, but chemically related odorants (geraniol, citronellol, citronellal and farnesol). The analysis identified a unique neural representation of the recruitment pheromone component compared to the other odorants that are predominantly emitted by flowers. The farnesol induced population activity in the AL allowed a reliable separation of farnesol from all other chemically related odor stimuli we tested. We conclude that the farnesol induced population activity may reflect a predetermined representation within the AL-neural network allowing efficient and fast extraction of a behaviorally relevant stimulus. Furthermore, the results show that population response analyses of multiple single AL-units may provide a powerful tool to identify distinct representations of behaviorally relevant odors.}, language = {en} } @phdthesis{Schmitt2004, author = {Schmitt, Thomas}, title = {Communication in the hymenoptera : chemistry, ecology and evolution}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-11267}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2004}, abstract = {Insects exhibit complex systems of communication with chemical signalling being the most important mode. Although there are many studies on chemical communication in insects, the evolution of chemical signals is not well understood. Due to the conflict of interests between individuals, different selective pressures might act on sender and receiver. In this thesis I investigate different types of communication where either the sender, the receiver or both parties yield benefits. These studies were conducted with one digger wasp species, honeybees, one chrysidid wasp, and three ant species. Senders might benefit by exploiting existing preferences of receivers. Such sensory exploitation might influence the evolution of male signals that are designed to attract females. The sex pheromone of male European beewolves Philanthus triangulum (Hymenoptera, Crabronidae) might have evolved according to the sensory exploitation hypothesis. A three-step scenario is supported by our studies. First, a major component of the honeybee alarm pheromone, (Z)-11-eicosen-1-ol, is also found on the cuticles and in the air surrounding foraging honeybees. Second, it could be shown, that (Z)-11- eicosen-1-ol plays a crucial role as kairomone for prey identification of honeybees by beewolf females. Third, a reanalysis of the beewolf male sex pheromone shows a remarkable similarity of compounds between the pheromone and the honeybee cuticle, besides the co-occurrence of (Z)-11-eisosen-ol. The majority of the cuticular hydrocarbons of honeybees occur also in the headspace of foraging workers. These results strongly support the hypothesis that beewolf males evolved a pheromone that exploits the females' pre-existing sensory sensitivity. In addition, the male sex pheromone shows a significantly higher similarity among brothers than among non-related individuals, which might enable beewolf females to discriminate against brothers and avoid detrimental effects of breeding. Together with the studies on the possible sensory exploitation this result shows that both, male and female beewolves probably gain more benefits than costs from the pheromone communication and, thus, the communication system as a whole can be regarded as cooperative. To maintain the reproductive division of labour in eusocial colonies, queens have to signal their presence and fecundity. In the ant Camponotus floridanus (Hymenoptera, Formicidae) queens mark their own eggs with a distinctive pattern of cuticular hydrocarbons. Two different hypotheses have been developed. One suggests a form of worker manipulation by the queen. The alternative hypothesis assumes a cooperative signal that provides information on the condition of the queen. The results of our investigation clearly favour the latter hypothesis. Chemical mimicry is a form of non-cooperative communication that benefits predominantly the sender. We provided conclusive evidence that the cockoo wasp, Hedychrum rutilans (Hymenoptera, Chrysididae), the primary brood parasitoid of Philanthus triangulum, evades recognition by beewolf females most probably by chemical mimicry of the odour of its host. Furthermore, the adaptation of the chemical signature in the social ant parasite Protomognathus americanus (Hymenoptera, Formicidae) to its Leptothorax (Hymenoptera, Formicidae) hosts was investigated. Although this parasite is principally adapted to its hosts' cuticular hydrocarbon profile, there are still pronounced differences between the profiles of parasites and hosts. This might be explained by the trade-off, which the parasites faces when confronted locally with two host species with different cuticular hydrocarbon profiles. Non-cooperative communication in the sense that only receivers benefit was discovered in the exploitation of honeybees volatile cuticular hydrocarbons by beewolf females. By using emitted (Z)-11-eicosen-1-ol as a kairomone, the receiver, the beewolf female, yields the benefits and the sender, the honeybee prey, bears all the costs. The results of these studies contribute to the understanding of the evolution of cooperative and non-cooperative communication with chemical signals taking into account differential benefits for sender and/or receiver.}, subject = {Hautfl{\"u}gler}, language = {en} } @article{ChristopherDUgelvigWiesenhoferetal.2018, author = {Christopher D., Pull and Ugelvig, Line V. and Wiesenhofer, Florian and Anna V., Grasse and Tragust, Simon and Schmitt, Thomas and Brown, Mark JF and Cremer, Sylvia}, title = {Destructive disinfection of infected brood prevents systemic disease spread in ant colonies}, series = {eLIFE}, volume = {7}, journal = {eLIFE}, doi = {10.7554/eLife.32073}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-223728}, pages = {e 32073, 1-29}, year = {2018}, abstract = {In social groups, infections have the potential to spread rapidly and cause disease outbreaks. Here, we show that in a social insect, the ant Lasius neglectus, the negative consequences of fungal infections (Metarhizium brunneum) can be mitigated by employing an efficient multicomponent behaviour, termed destructive disinfection, which prevents further spread of the disease through the colony. Ants specifically target infected pupae during the pathogens non-contagious incubation period, utilising chemical 'sickness cues' emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a metazoan body that specifically targets and eliminates infected cells, ants destroy infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, in an analogous fashion, the same principles of disease defence apply at different levels of biological organisation.}, language = {en} } @article{MaihoffBohlkeBrockmannetal.2022, author = {Maihoff, Fabienne and Bohlke, Kyte and Brockmann, Axel and Schmitt, Thomas}, title = {Increased complexity of worker CHC profiles in Apis dorsata correlates with nesting ecology}, series = {PLoS ONE}, volume = {17}, journal = {PLoS ONE}, number = {7}, doi = {10.1371/journal.pone.0271745}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301353}, year = {2022}, abstract = {Cuticular hydrocarbons (CHC) are known to serve as discrimination cues and will trigger defence behaviour in a plethora of eusocial insects. However, little is known how about nestmate recognition ability selects for CHC diversification. In this study we investigate differences in CHC composition of four major honey bee species with respect to the differences in their nesting behavior. In contrast to A. mellifera, A. cerana and A. florea, the giant honey bee A. dorsata prefers to build their nests in aggregations with very small spatial distances between nests, which increases the probability of intrusions. Thus, A. dorsata exhibits a particularly challenging nesting behavior which we hypothesize should be accompanied with an improved nestmate recognition system. Comparative analyses of the worker CHC profiles indicate that A. dorsata workers exhibit a unique and more complex CHC profile than the other three honey bee species. This increased complexity is likely based on a developmental process that retains the capability to synthesize methyl-branched hydrocarbons as adults. Furthermore, two sets of behavioral experiments provide evidence that A. dorsata shows an improved nestmate discrimination ability compared to the phylogenetically ancestral A. florea, which is also open-nesting but does not form nest aggregations. The results of our study suggest that ecological traits like nesting in aggregation might be able to drive CHC profile diversification even in closely related insect species.}, 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{DiaoMoussetHorsburghetal.2016, author = {Diao, Wenwen and Mousset, Mathilde and Horsburgh, Gavin J. and Vermeulen, Cornelis J. and Johannes, Frank and van de Zande, Louis and Ritchie, Michael G. and Schmitt, Thomas and Beukeboom, Leo W.}, title = {Quantitative Trait Locus Analysis of Mating Behavior and Male Sex Pheromones in Nasonia Wasps}, series = {G3: Genes Genomes Genetics}, volume = {6}, journal = {G3: Genes Genomes Genetics}, number = {6}, doi = {10.1534/g3.116.029074}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165412}, pages = {1549-1562}, year = {2016}, abstract = {A major focus in speciation genetics is to identify the chromosomal regions and genes that reduce hybridization and gene flow. We investigated the genetic architecture of mating behavior in the parasitoid wasp species pair Nasonia giraulti and Nasonia oneida that exhibit strong prezygotic isolation. Behavioral analysis showed that N. oneida females had consistently higher latency times, and broke off the mating sequence more often in the mounting stage when confronted with N. giraulti males compared with males of their own species. N. oneida males produce a lower quantity of the long-range male sex pheromone (4R,5S)-5-hydroxy-4-decanolide (RS-HDL). Crosses between the two species yielded hybrid males with various pheromone quantities, and these males were used in mating trials with females of either species to measure female mate discrimination rates. A quantitative trait locus (QTL) analysis involving 475 recombinant hybrid males (F2), 2148 reciprocally backcrossed females (F3), and a linkage map of 52 equally spaced neutral single nucleotide polymorphism (SNP) markers plus SNPs in 40 candidate mating behavior genes revealed four QTL for male pheromone amount, depending on partner species. Our results demonstrate that the RS-HDL pheromone plays a role in the mating system of N. giraulti and N. oneida, but also that additional communication cues are involved in mate choice. No QTL were found for female mate discrimination, which points at a polygenic architecture of female choice with strong environmental influences.}, language = {en} } @article{BuellesbachDiaoSchmittetal.2022, author = {Buellesbach, Jan and Diao, Wenwen and Schmitt, Thomas and Beukeboom, Leo W.}, title = {Micro-climate correlations and conserved sexual dimorphism of cuticular hydrocarbons in European populations of the jewel wasp Nasonia vitripennis}, series = {Ecological Entomology}, volume = {47}, journal = {Ecological Entomology}, number = {1}, doi = {10.1111/een.13089}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262770}, pages = {38 -- 51}, year = {2022}, abstract = {1. Protection against desiccation and chemical communication are two fundamental functions of cuticular hydrocarbons (CHCs) in insects. In the parasitoid jewel wasp Nasonia vitripennis (Walker), characterised by a cosmopolitan distribution through largely different environments, CHCs function as universally recognised female sex pheromones. However, CHC uniformity as basis for sexual recognition may conflict with the desiccation protection function, expected to display considerable flexibility through adaptation to different environmental conditions. 2. We compared male and female CHC profiles of N. vitripennis across a wide latitudinal gradient in Europe and correlated their CHC variation with climatic factors associated with desiccation. Additionally, we tested male mate discrimination behaviour between populations to detect potential variations in female sexual attractiveness. 3. Results did not conform to the general expectation that longer, straight-chain CHCs occur in higher proportions in warmer and drier climates. Instead, unexpected environmental correlations of intermediate chain-length CHCs (C31) were found exclusively in females, potentially reflecting the different life histories of the sexes in N. vitripennis. 4. Furthermore, we found no indication of population-specific male mate preference, confirming the stability of female sexual attractiveness, likely conveyed through their CHC profiles. C31 mono- and C33 di-methyl-branched alkanes were consistently and most strongly associated with sexual dimorphism, suggesting their potential role in encoding the female-specific sexual signalling function. 5. Our study sheds light on how both adaptive flexibility and conserved sexual attractiveness can potentially be integrated and encoded in CHC profiles of N. vitripennis females across a wide distribution range in Europe.}, language = {en} } @article{BuellesbachVetterSchmitt2018, author = {Buellesbach, Jan and Vetter, Sebastian G. and Schmitt, Thomas}, title = {Differences in the reliance on cuticular hydrocarbons as sexual signaling and species discrimination cues in parasitoid wasps}, series = {Frontiers in Zoology}, volume = {15}, journal = {Frontiers in Zoology}, doi = {10.1186/s12983-018-0263-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-221702}, year = {2018}, abstract = {Background Cuticular hydrocarbons (CHC) have been documented to play crucial roles as species- and sex-specific cues in the chemical communication systems of a wide variety of insects. However, whether they are sufficient by themselves as the sole cue triggering sexual behavior as well as preference of con- over heterospecific mating partners is rarely assessed. We conducted behavioral assays in three representative species of parasitoid wasps (Hymenoptera: Pteromalidae) to determine their reliance on CHC as species-specific sexual signaling cues. Results We found a surprising degree of either unspecific or insufficient sexual signaling when CHC are singled out as recognition cues. Most strikingly, the cosmopolitan species Nasonia vitripennis, expected to experience enhanced selection pressure to discriminate against other co-occurring parasitoids, did not discriminate against CHC of a partially sympatric species from another genus, Trichomalopsis sarcophagae. Focusing on the latter species, in turn, it became apparent that CHC are even insufficient as the sole cue triggering conspecific sexual behavior, hinting at the requirement of additional, synergistic sexual cues particularly important in this species. Finally, in the phylogenetically and chemically most divergent species Muscidifurax uniraptor, we intriguingly found both CHC-based sexual signaling as well as species discrimination behavior intact although this species is naturally parthenogenetic with sexual reproduction only occurring under laboratory conditions. Conclusions Our findings implicate a discrepancy in the reliance on and specificity of CHC as sexual cues in our tested parasitioid wasps. CHC profiles were not sufficient for unambiguous discrimination and preference behavior, as demonstrated by clear cross-attraction between some of our tested wasp genera. Moreover, we could show that only in T. sarcophagae, additional behavioral cues need to be present for triggering natural mating behavior, hinting at an interesting shift in signaling hierarchy in this particular species. This demonstrates the importance of integrating multiple, potentially complementary signaling modalities in future studies for a better understanding of their individual contributions to natural sexual communication behavior.}, language = {en} } @article{PolidoriBallesterosWurdacketal.2020, author = {Polidori, Carlo and Ballesteros, Yolanda and Wurdack, Mareike and As{\´i}s, Josep Daniel and Tormos, Jos{\´e} and Ba{\~n}os-Pic{\´o}n, Laura and Schmitt, Thomas}, title = {Low host specialization in the cuckoo wasp, Parnopes grandior, weakens chemical mimicry but does not lead to local adaption}, series = {Insects}, volume = {11}, journal = {Insects}, number = {2}, issn = {2075-4450}, doi = {10.3390/insects11020136}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200651}, year = {2020}, abstract = {Insect brood parasites have evolved a variety of strategies to avoid being detected by their hosts. Few previous studies on cuckoo wasps (Hymenoptera: Chrysididae), which are natural enemies of solitary wasps and bees, have shown that chemical mimicry, i.e., the biosynthesis of cuticular hydrocarbons (CHC) that match the host profile, evolved in several species. However, mimicry was not detected in all investigated host-parasite pairs. The effect of host range as a second factor that may play a role in evolution of mimicry has been neglected, since all previous studies were carried out on host specialists and at nesting sites where only one host species occurred. Here we studied the cuckoo wasp Parnopes grandior, which attacks many digger wasp species of the genus Bembix (Hymenoptera: Crabronidae). Given its weak host specialization, P. grandior may either locally adapt by increasing mimicry precision to only one of the sympatric hosts or it may evolve chemical insignificance by reducing the CHC profile complexity and/or CHCs amounts. At a study site harbouring three host species, we found evidence for a weak but appreciable chemical deception strategy in P. grandior. Indeed, the CHC profile of P. grandior was more similar to all sympatric Bembix species than to a non-host wasp species belonging to the same tribe as Bembix. Furthermore, P. grandior CHC profile was equally distant to all the hosts' CHC profiles, thus not pointing towards local adaptation of the CHC profile to one of the hosts' profile. We conducted behavioural assays suggesting that such weak mimicry is sufficient to reduce host aggression, even in absence of an insignificance strategy, which was not detected. Hence, we finally concluded that host range may indeed play a role in shaping the level of chemical mimicry in cuckoo wasps.}, language = {en} } @article{DrescherKleinSchmittetal.2019, author = {Drescher, Nora and Klein, Alexandra-Maria and Schmitt, Thomas and Leonhardt, Sara Diana}, title = {A clue on bee glue: New insight into the sources and factors driving resin intake in honeybees (Apis mellifera)}, series = {PLoS ONE}, volume = {14}, journal = {PLoS ONE}, number = {2}, doi = {10.1371/journal.pone.0210594}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200935}, pages = {e0210594}, year = {2019}, abstract = {Honeybees (Apis mellifera) are threatened by numerous pathogens and parasites. To prevent infections they apply cooperative behavioral defenses, such as allo-grooming and hygiene, or they use antimicrobial plant resin. Resin is a chemically complex and highly variable mixture of many bioactive compounds. Bees collect the sticky material from different plant species and use it for nest construction and protection. Despite its importance for colony health, comparatively little is known about the precise origins and variability in resin spectra collected by honeybees. To identify the botanical resin sources of A. mellifera in Western Europe we chemically compared resin loads of individual foragers and tree resins. We further examined the resin intake of 25 colonies from five different apiaries to assess the effect of location on variation in the spectra of collected resin. Across all colonies and apiaries, seven distinct resin types were categorized according to their color and chemical composition. Matches between bee-collected resin and tree resin indicated that bees used poplar (Populus balsamifera, P. x canadensis), birch (Betula alba), horse chestnut (Aesculus hippocastanum) and coniferous trees (either Picea abies or Pinus sylvestris) as resin sources. Our data reveal that honeybees collect a comparatively broad and variable spectrum of resin sources, thus assuring protection against a variety of antagonists sensitive to different resins and/or compounds. We further unravel distinct preferences for specific resins and resin chemotypes, indicating that honeybees selectively search for bioactive resin compounds.}, language = {en} } @article{UllmannBanksSchmittetal.2017, author = {Ullmann, Tobias and Banks, Sarah N. and Schmitt, Andreas and Jagdhuber, Thomas}, title = {Scattering characteristics of X-, C- and L-Band PolSAR data examined for the tundra environment of the Tuktoyaktuk Peninsula, Canada}, series = {Applied Sciences}, volume = {7}, journal = {Applied Sciences}, number = {6}, doi = {10.3390/app7060595}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158362}, pages = {595}, year = {2017}, abstract = {In this study, polarimetric Synthetic Aperture Radar (PolSAR) data at X-, C- and L-Bands, acquired by the satellites: TerraSAR-X (2011), Radarsat-2 (2011), ALOS (2010) and ALOS-2 (2016), were used to characterize the tundra land cover of a test site located close to the town of Tuktoyaktuk, NWT, Canada. Using available in situ ground data collected in 2010 and 2012, we investigate PolSAR scattering characteristics of common tundra land cover classes at X-, C- and L-Bands. Several decomposition features of quad-, co-, and cross-polarized data were compared, the correlation between them was investigated, and the class separability offered by their different feature spaces was analyzed. Certain PolSAR features at each wavelength were sensitive to the land cover and exhibited distinct scattering characteristics. Use of shorter wavelength imagery (X and C) was beneficial for the characterization of wetland and tundra vegetation, while L-Band data highlighted differences of the bare ground classes better. The Kennaugh Matrix decomposition applied in this study provided a unified framework to store, process, and analyze all data consistently, and the matrix offered a favorable feature space for class separation. Of all elements of the quad-polarized Kennaugh Matrix, the intensity based elements K0, K1, K2, K3 and K4 were found to be most valuable for class discrimination. These elements contributed to better class separation as indicated by an increase of the separability metrics squared Jefferys Matusita Distance and Transformed Divergence. The increase in separability was up to 57\% for Radarsat-2 and up to 18\% for ALOS-2 data.}, language = {en} } @article{StreinzerChakravortyNeumayeretal.2019, author = {Streinzer, Martin and Chakravorty, Jharna and Neumayer, Johann and Megu, Karsing and Narah, Jaya and Schmitt, Thomas and Bharti, Himender and Spaethe, Johannes and Brockmann, Axel}, title = {Species composition and elevational distribution of bumble bees (Hymenoptera, Apidae, Bombus Latreille) in the East Himalaya, Arunachal Pradesh, India}, series = {ZooKeys}, volume = {851}, journal = {ZooKeys}, doi = {10.3897/zookeys.851.32956}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201937}, pages = {71-89}, year = {2019}, abstract = {The East Himalaya is one of the world's most biodiverse ecosystems. However, very little is known about the abundance and distribution of many plant and animal taxa in this region. Bumble bees are a group of cold-adapted and high elevation insects that fulfil an important ecological and economical function as pollinators of wild and agricultural flowering plants and crops. The Himalayan mountain range provides ample suitable habitats for bumble bees. Systematic study of Himalayan bumble bees began a few decades ago and the main focus has centred on the western region, while the eastern part of the mountain range has received little attention and only a few species have been verified. During a three-year survey, more than 700 bumble bee specimens of 21 species were collected in Arunachal Pradesh, the largest of the north-eastern states of India. The material included a range of species that were previously known from a limited number of collected specimens, which highlights the unique character of the East Himalayan ecosystem. Our results are an important first step towards a future assessment of species distribution, threat, and conservation. Clear elevation patterns of species diversity were observed, which raise important questions about the functional adaptations that allow bumble bees to thrive in this particularly moist region in the East Himalaya.}, language = {en} } @article{SprengerMuesseHartkeetal.2021, author = {Sprenger, Philipp P. and M{\"u}sse, Christian and Hartke, Juliane and Feldmeyer, Barbara and Schmitt, Thomas and Gebauer, Gerhard and Menzel, Florian}, title = {Dinner with the roommates: trophic niche differentiation and competition in a mutualistic ant-ant association}, series = {Ecological Entomology}, volume = {46}, journal = {Ecological Entomology}, number = {3}, doi = {10.1111/een.13002}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-228215}, pages = {562 -- 572}, year = {2021}, abstract = {1. The potential for competition is highest among species in close association. Despite net benefits for both parties, mutualisms can involve costs, including food competition. This might be true for the two neotropical ants Camponotus femoratus and Crematogaster levior, which share the same nest in a presumably mutualistic association (parabiosis). 2. While each nest involves one Crematogaster and one Camponotus partner, both taxa were recently found to comprise two cryptic species that show no partner preferences and seem ecologically similar. Since these cryptic species often occur in close sympatry, they might need to partition their niches to avoid competitive exclusion. 3. Here, we investigated first, is there interference competition between parabiotic Camponotus and Crematogaster, and do they prefer different food sources under competition? And second, is there trophic niche partitioning between the cryptic species of either genus? 4. Using cafeteria experiments, neutral lipid fatty acid and stable isotope analyses, we found evidence for interference competition, but also trophic niche partitioning between Camponotus and Crematogaster. Both preferred protein- and carbohydrate-rich baits, but at protein-rich baits Ca. femoratus displaced Cr. levior over time, suggesting a potential discovery-dominance trade-off between parabiotic partners. Only limited evidence was found for trophic differentiation between the cryptic species of each genus. 5. Although we cannot exclude differentiation in other niche dimensions, we argue that neutral dynamics might mediate the coexistence of cryptic species. This model system is highly suitable for further studies of the maintenance of species diversity and the role of mutualisms in promoting species coexistence.}, language = {en} } @article{RauSchmittBergetal.2018, author = {Rau, Monika and Schmitt, Johannes and Berg, Thomas and Kremer, Andreas E. and Stieger, Bruno and Spanaus, Katharina and Bengsch, Bertram and Romero, Marta R. and Marin, Jose J. and Keitel, Verena and Klinker, Hartwig and Tony, Hans-Peter and M{\"u}llhaupt, Beat and Geier, Andreas}, title = {Serum IP-10 levels and increased DPPIV activity are linked to circulating CXCR3+ T cells in cholestatic HCV patients}, series = {PLoS ONE}, volume = {13}, journal = {PLoS ONE}, number = {12}, doi = {10.1371/journal.pone.0208225}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177674}, pages = {e0208225}, year = {2018}, abstract = {Background \& aims Serum interferon-gamma-inducible protein-10 (IP-10) is elevated in cholestatic liver diseases and predicts response to antiviral therapy in patients with chronic hepatitis C virus (HCV) infection. Dipeptidylpeptidase 4 (DPPIV) cleaves active IP-10 into an inactive form, which inhibits recruitment of CXCR3+ T cells to the liver. In this study the link between IP-10 levels, DPPIV activity in serum and CXCR3+ T cells is analysed in cholestatic and non-cholestatic liver patients. Methods In serum DPPIV activity (by enzymatic assay), IP-10 (by ELISA) and bile acids (BA) (by enzymatic assay) were analysed in 229 naive HCV genotype (GT) 1 patients and in 16 patients with cholestatic liver disease. In a prospective follow-up (FU) cohort of 27 HCV GT 1 patients peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ cells were measured by FACS. Results In 229 HCV patients serum IP-10 levels correlated positively to DPPIV serum activity. Higher IP-10 levels and DPPIV activity were detected in cholestatic and in cirrhotic HCV patients. Increased IP-10 serum levels were associated with therapeutic non-response to antiviral treatment with pegylated-interferon and ribavirin. In the HCV FU cohort elevated IP-10 serum levels and increased BA were associated with higher frequencies of peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ T cells. Positive correlation between serum IP-10 levels and DPPIV activity was likewise validated in patients with cholestatic liver diseases. Conclusions A strong correlation between elevated serum levels of IP-10 and DPPIV activity was seen in different cholestatic patient groups. Furthermore, in cholestatic HCV patients a functional link to increased numbers of peripheral CXCR3+ immune cells could be observed. The source of DPPIV release in cholestatic patients remains open.}, 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} }