Browsing by Subject "HYMENOPTERA"

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  • Ramage, Thibault; Martins-Simoes, Patricia; Mialdea, Gladys; Allemand, Roland; Duplouy, Anne; Rousse, Pascal; Davies, Neil; Roderick, George K.; Charlat, Sylvain (2017)
    We report here on the taxonomic and molecular diversity of 10 929 terrestrial arthropod specimens, collected on four islands of the Society Archipelago, French Polynesia. The survey was part of the 'SymbioCode Project' that aims to establish the Society Islands as a natural laboratory in which to investigate the flux of bacterial symbionts (e.g., Wolbachia) and other genetic material among branches of the arthropod tree. The sample includes an estimated 1127 species, of which 1098 included at least one DNA-barcoded specimen and 29 were identified to species level using morphological traits only. Species counts based on molecular data emphasize that some groups have been understudied in this region and deserve more focused taxonomic effort, notably Diptera, Lepidoptera and Hymenoptera. Some taxa that were also subjected to morphological scrutiny reveal a consistent match between DNA and morphology-based species boundaries in 90% of the cases, with a larger than expected genetic diversity in the remaining 10%. Many species from this sample are new to this region or are undescribed. Some are under description, but many await inspection by motivated experts, who can use the online images or request access to ethanol-stored specimens.
  • Rutkowski, Tomasz; Maak, Istvsn; Vepsäläinen, Kari; Trigos-Peral, Gema; Stephan, Wojciech; Wojtaszyn, Grzegorz; Czechowski, Wojciech (2019)
    Successful evacuation of a peculiar 'colony' of the wood ant Formica polyctena Forst., for years trapped within an old bunker previously used for storing nuclear weapons (see Czechowski et al. 2016), is reported. Using an experimentally installed boardwalk, the imprisoned ants managed to get through the ventilation pipe to their maternal nest on the top of the bunker. In our previous report, we left open the question of how the 'colony' could survive seemingly without food. Here we show that the 'colony' in the bunker survived and grew thanks to an influx of workers from the source nest above the bunker and mass consumption of corpses of the imprisoned nestmates.
  • Wirta, Helena K.; Hebert, Paul D. N.; Kaartinen, Riikka; Prosser, Sean W.; Varkonyi, Gergely; Roslin, Tomas (2014)
  • Mutanen, Marko; Ovaskainen, Otso; Várkonyi, Gergely; Itämies, Juhani; Prosser, Sean W. J.; Hebert, Paul D. N.; Hanski, Ilkka (2020)
    Abstract It has been hypothesised that the 2-year oscillations in abundance of Xestia moths are mediated by interactions with 1-year Ophion parasitoid wasps. We tested this hypothesis by modelling a 35-year time series of Xestia and Ophion from Northern Finland. Additionally, we used DNA barcoding to ascertain the species diversity of Ophion and targeted amplicon sequencing of their gut contents to confirm their larval hosts. Modelling of the time-series data strongly supported the hypothesised host?parasitoid dynamics and that periodic occurrence of Xestia moths is mediated by Ophion. DNA barcodes revealed that Ophion included five species rather than just one while targeted amplicon sequencing verified that Ophion does parasitise Xestia. At least one Ophion species employs 1-year Syngrapha interrogationis as an alternate host, but it did not detectably affect Xestia?Ophion dynamics. We also demonstrate the previously unrecognised complexity of this system due to cryptic parasitoid diversity.
  • Klein, Antonia; Schultner, Eva; Lowak, Helena; Schrader, Lukas; Heinze, Juergen; Holman, Luke; Oettler, Jan (2016)
    The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the 'theory of facilitated variation', we identify sex differentiation pathways as promising candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx) and a kruppel homolog 2 (kr-h2) with putative regulatory function, exhibit both sex and morph-specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues), and that their inherent switch-like and epistatic behavior facilitated signal transfer to downstream targets, thus allowing them to control differential development into morphological castes.
  • Rautiala, Petri; Helantera, Heikki; Puurtinen, Mikael (2019)
    Evolution of altruistic behavior was a hurdle for the logic of Darwinian evolution. Soon after Hamilton formalized the concept of inclusive fitness, which explains how altruism can evolve, he suggested that the high sororal relatedness brought by haplodiploidy could be why Hymenopterans have a high prevalence in eusocial species, and why helpers in Hymenoptera are always female. Later it was noted that in order to capitalize on the high sororal relatedness, helpers would need to direct help toward sisters, and this would bias the population sex ratio. Under a 1:3 males:females sex ratio, the inclusive fitness valuation a female places on her sister, brother, and an own offspring are equalapparently removing the benefit of helping over independent reproduction. Based on this argumentation, haplodiploidy hypothesis has been considered a red herring. However, here we show that when population sex ratio, cost of altruism, and population growth rate are considered together, haplodiploidy does promote female helping even with female-biased sex ratio, due the lowered cost of altruism in such populations. Our analysis highlights the need to re-evaluate the role of haplodiploidy in the evolution of helping, and the importance of fully exploring the model assumptions when comparing interactions of population sex ratios and social behaviors.
  • Peignier, Mélissa; Pokorny, Tamara; Heinze, Jürgen; Lindgren, Rosanna; Helanterä, Heikki; Schultner, Eva (2019)
    Social insects live in highly complex societies with efficient communication systems. Begging is one display commonly used by offspring to signal their nutritional state, however begging behavior has received very little attention in social insects. Theory predicts that begging can be either an honest (i.e., honest-signaling strategy) or a dishonest (i.e., scrambling competition) signal of need, with dishonest signals expected to be more likely when relatedness within the group is low. To investigate the presence and honesty of begging, as well as the nature of the involved signals, we used a comparative approach with four species of the ant genus Formica known to differ in the degree of intra-colony relatedness. We investigated the behavior of starved and non-starved larvae of F. aquilonia, F. pressilabris (both low intra-colony relatedness), F. exsecta (intermediate relatedness), and F. fusca (high relatedness). In addition, we assessed the attraction of conspecific workers toward odors extracted from these two classes of larvae and analyzed the larval cuticular hydrocarbon profiles. We found that in F. fusca and F. exsecta, larvae signaled significantly more when starved. In contrast, larvae of F. aquilonia signaled significantly more when they were non-starved, while there was no significant difference in the behavior of starved vs. non-starved larvae in F. pressilabris. Our results show that workers were not preferentially attracted to the odor of starved larvae, and we also did not detect any differences between the cuticular hydrocarbon profiles of starved and non-starved larvae. Overall, this study demonstrates among species variation in larval hunger signaling in Formica ants, and encourages further studies to confirm the link between kin structure variation and the honesty of begging signals.
  • Nair, Abhilash; Nonaka, Etsuko; van Nouhuys, Saskya (2018)
    Climate change can increase spatial synchrony of population dynamics, leading to large-scale fluctuation that destabilizes communities. High trophic level species such as parasitoids are disproportionally affected because they depend on unstable resources. Most parasitoid wasps have complementary sex determination, producing sterile males when inbred, which can theoretically lead to population extinction via the diploid male vortex (DMV). We examined this process empirically using a hyperparasitoid population inhabiting a spatially structured host population in a large fragmented landscape. Over four years of high host butterfly metapopulation fluctuation, diploid male production by the wasp increased, and effective population size declined precipitously. Our multitrophic spatially structured model shows that host population fluctuation can cause local extinctions of the hyperparasitoid because of the DMV. However, regionally it persists because spatial structure allows for efficient local genetic rescue via balancing selection for rare alleles carried by immigrants. This is, to our knowledge, the first empirically based study of the possibility of the DMV in a natural host–parasitoid system.
  • Kankaanpaa, Tuomas; Vesterinen, Eero; Hardwick, Bess; Schmidt, Niels M.; Andersson, Tommi; Aspholm, Paul E.; Barrio, Isabel C.; Beckers, Niklas; Bety, Joel; Birkemoe, Tone; DeSiervo, Melissa; Drotos, Katherine H.; Ehrich, Dorothee; Gilg, Olivier; Gilg, Vladimir; Hein, Nils; Hoye, Toke T.; Jakobsen, Kristian M.; Jodouin, Camille; Jorna, Jesse; Kozlov, Mikhail; Kresse, Jean-Claude; Leandri-Breton, Don-Jean; Lecomte, Nicolas; Loonen, Maarten; Marr, Philipp; Monckton, Spencer K.; Olsen, Maia; Otis, Josee-Anne; Pyle, Michelle; Roos, Ruben E.; Raundrup, Katrine; Rozhkova, Daria; Sabard, Brigitte; Sokolov, Aleksandr; Sokolova, Natalia; Solecki, Anna M.; Urbanowicz, Christine; Villeneuve, Catherine; Vyguzova, Evgenya; Zverev, Vitali; Roslin, Tomas (2020)
    Climatic impacts are especially pronounced in the Arctic, which as a region is warming twice as fast as the rest of the globe. Here, we investigate how mean climatic conditions and rates of climatic change impact parasitoid insect communities in 16 localities across the Arctic. We focus on parasitoids in a widespread habitat,Dryasheathlands, and describe parasitoid community composition in terms of larval host use (i.e., parasitoid use of herbivorous Lepidoptera vs. pollinating Diptera) and functional groups differing in their closeness of host associations (koinobionts vs. idiobionts). Of the latter, we expect idiobionts-as being less fine-tuned to host development-to be generally less tolerant to cold temperatures, since they are confined to attacking hosts pupating and overwintering in relatively exposed locations. To further test our findings, we assess whether similar climatic variables are associated with host abundances in a 22 year time series from Northeast Greenland. We find sites which have experienced a temperature rise in summer while retaining cold winters to be dominated by parasitoids of Lepidoptera, with the reverse being true for the parasitoids of Diptera. The rate of summer temperature rise is further associated with higher levels of herbivory, suggesting higher availability of lepidopteran hosts and changes in ecosystem functioning. We also detect a matching signal over time, as higher summer temperatures, coupled with cold early winter soils, are related to high herbivory by lepidopteran larvae, and to declines in the abundance of dipteran pollinators. Collectively, our results suggest that in parts of the warming Arctic,Dryasis being simultaneously exposed to increased herbivory and reduced pollination. Our findings point to potential drastic and rapid consequences of climate change on multitrophic-level community structure and on ecosystem functioning and highlight the value of collaborative, systematic sampling effort.
  • Perez-Lachaud, Gabriela; Jahyny, Benoit J. B.; Ståhls, Gunilla; Rotheray, Graham; Delabie, Jacques H. C.; Lachaud, Jean-Paul (2017)
    The myrmecophile larva of the dipteran taxon Nothomicrodon Wheeler is rediscovered, almost a century after its original description and unique report. The systematic position of this dipteran has remained enigmatic due to the absence of reared imagos to confirm indentity. We also failed to rear imagos, but we scrutinized entire nests of the Brazilian arboreal dolichoderine ant Azteca chartifex which, combined with morphological and molecular studies, enabled us to establish beyond doubt that Nothomicrodon belongs to the Phoridae (Insecta: Diptera), not the Syrphidae where it was first placed, and that the species we studied is an endoparasitoid of the larvae of A. chartifex, exclusively attacking sexual female (gyne) larvae. Northomicrodon parasitism can exert high fitness costs to a host colony. Our discovery adds one more case to the growing number of phorid taxa known to parasitize ant larvae and suggests that many others remain to be discovered. Our findings and literature review confirm that the Phoridae is the only taxon known that parasitizes both adults and the immature stages of different castes of ants, thus threatening ants on all fronts.
  • Bos, Nick; Pulliainen, Unni; Sundström, Liselotte; Freitak, Dalial (2016)
    Starvation is one of the most common and severe stressors in nature. Not only does it lead to death if not alleviated, it also forces the starved individual to allocate resources only to the most essential processes. This creates energetic trade-offs which can lead to many secondary challenges for the individual. These energetic trade-offs could be exacerbated in inbred individuals, which have been suggested to have a less efficient metabolism. Here, we studied the effect of inbreeding on starvation resistance in a natural population of Formica exsecta ants, with a focus on survival and tissue-specific expression of stress, metabolism and immunity-related genes. Starvation led to large tissue-specific changes in gene expression, but inbreeding had little effect on most of the genes studied. Our results illustrate the importance of studying stress responses in different tissues instead of entire organisms.
  • Thorogood, Rose; Spottiswoode, Claire N.; Portugal, Steven J.; Gloag, Ros (2019)
    Obligate brood-parasitic cheats have fascinated natural historians since ancient times. Passing on the costs of parental care to others occurs widely in birds, insects and fish, and often exerts selection pressure on hosts that in turn evolve defences. Brood parasites have therefore provided an illuminating system for researching coevolution. Nevertheless, much remains unknown about howecology and evolutionary history constrain or facilitate brood parasitism, or the mechanisms that shape or respond to selection. In this special issue, we bring together examples fromacross the animal kingdomto illustrate the diverseways in which recent research is addressing these gaps. This special issue also considers how research on brood parasitism may benefit from, and in turn inform, related fields such as social evolution and immunity. Here, we argue that progress in our understanding of coevolution would benefit from the increased integration of ideas across taxonomic boundaries and across Tinbergen's Four Questions: mechanism, ontogeny, function and phylogeny of brood parasitism. We also encourage renewed vigour in uncovering the natural history of the majority of the world's brood parasites that remain little-known. Indeed, it seems very likely that some of nature's brood parasites remain entirely unknown, because otherwise we are left with a puzzle: if parental care is so costly, why is brood parasitism not more common? This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.
  • Nonaka, Etsuko; Kaitala, Veijo (2020)
    Many parasitoids have single-locus complementary sex determination (sl-CSD), which produces sterile or inviable males when homozygous at the sex determining locus. A previous study theoretically showed that small populations have elevated risks of extinction due to the positive feedback between inbreeding and small population size, referred to as the diploid male vortex. A few modeling studies have suggested that the diploid male vortex may not be as common because balancing selection at sex determining loci tends to maintain high allelic diversity in spatially structured populations. However, the generality of the conclusion is yet uncertain, as they were drawn either from models developed for particular systems or from a general-purpose competition model. To attest the conclusion, we study several well-studied host-parasitoid models that incorporate functional response specifying the number of attacked hosts given a host density and derive the conditions for a diploid male vortex in a single population. Then, we develop spatially structured individual-based versions of the models to include female behavior, diploid male fertility, and temporal fluctuations. The results show that producing a handful of successful offspring per female parasitoid could enable parasitoid persistence when a typical number of CSD alleles are present. The effect of functional response depends on the levels of fluctuations in host abundance, and inviable or partially fertile diploid males and a small increase in dispersal can alleviate the risk of a diploid male vortex. Our work supports the generality of effective genetic rescue in spatially connected parasitoid populations with sl-CSD. However, under more variable climate, the efficacy of the CSD mechanism may substantially decline.
  • Pulliainen, Outi Unni Inkeri; Helanterä, Heikki Oskari; Sundström, Liselotte; Schultner, Eva Kristina (2019)
    Temporary social parasite ant queens initiate new colonies by entering colonies of host species, where they begin laying eggs. As the resident queen can be killed during this process, host colonies may lose their entire future reproductive output. Selection thus favours the evolution of defence mechanisms, before and after parasite intrusion. Most studies on social parasites focus on host worker discrimination of parasite queens and their offspring. However, ant larvae can also influence brood composition by consuming eggs. This raises the question whether host larvae can aid in preventing colony takeover by consuming eggs laid by parasite queens. To test whether larvae could play a role in anti-parasite defence, we compared the rates at which larvae of a common host species, Formica fusca, consumed eggs laid by social parasite, non-parasite, nest-mate, or conspecific non-nest-mate queens. Larvae consumed social parasite eggs more than eggs laid by a heterospecific non-parasite queen, irrespective of the chemical distance between the egg cuticular profiles. Also, larvae consumed eggs laid by conspecific non-nest-mate queens more than those laid by nest-mate queens. Our study suggests that larvae may act as players in colony defence against social parasitism, and that social parasitism is a key factor shaping discrimination behaviour in ants.
  • Duplouy, Anne; Pranter, Robin; Warren-Gash, Haydon; Tropek, Robert; Wahlberg, Niklas (2020)
    Background Phylogenetically closely related strains of maternally inherited endosymbiotic bacteria are often found in phylogenetically divergent, and geographically distant insect host species. The interspecies transfer of the symbiont Wolbachia has been thought to have occurred repeatedly, facilitating its observed global pandemic. Few ecological interactions have been proposed as potential routes for the horizontal transfer of Wolbachia within natural insect communities. These routes are however likely to act only at the local scale, but how they may support the global distribution of some Wolbachia strains remains unclear. Results Here, we characterize the Wolbachia diversity in butterflies from the tropical forest regions of central Africa to discuss transfer at both local and global scales. We show that numerous species from both the Mylothris (family Pieridae) and Bicyclus (family Nymphalidae) butterfly genera are infected with similar Wolbachia strains, despite only minor interclade contacts across the life cycles of the species within their partially overlapping ecological niches. The phylogenetic distance and differences in resource use between these genera rule out the role of ancestry, hybridization, and shared host-plants in the interspecies transfer of the symbiont. Furthermore, we could not identify any shared ecological factors to explain the presence of the strains in other arthropod species from other habitats, or even ecoregions. Conclusion Only the systematic surveys of the Wolbachia strains from entire species communities may offer the material currently lacking for understanding how Wolbachia may transfer between highly different and unrelated hosts, as well as across environmental scales.
  • Nouhaud, Pierre; Blanckaert, Alexandre; Bank, Claudia; Kulmuni, Jonna (2020)
    Hybridization has broad evolutionary consequences, from fueling or counteracting speciation to facilitating adaptation to novel environments. Hybridization and subsequent introgression appear widespread along the tree of life. However, our understanding of how distinct evolutionary forces shape admixed genomes and the fate of introgressed genetic variants remains scarce. Most admixture research in animals has focused on diploid organisms. Wepropose that haplodiploid organisms can help resolve open questions about the genomic consequences of hybridization in natural populations. The ploidy difference between haploid males and diploid females, the availability of genome-wide male haplotypes, and ongoing cases of admixture make haplodiploid organisms promising models to improve our knowledge with regards to the evolution of hybrid genomes.
  • Huang, Yunxian; Hatakeyama, Masatsugu; Shimmi, Osamu (2018)
    Wing venation among insects serves as an excellent model to address how diversified patterns are produced. Previous studies suggest that evolutionarily conserved Decapentaplegic (Dpp)/Bone Morphogenetic Protein (BMP) signal plays a critical role in wing vein development in the dipteran Drosophila melanogaster and the hymenopteran sawfly Athalia rosae. In sawfly, dpp is ubiquitously expressed in the wing during prepupal stages, but Dpp/BMP signal is localized in the future vein cells. Since localized BMP signaling involves BMP binding protein Crossveinless (Cv), redistribution of BMP ligands appears to be crucial for sawfly wing vein formation. However, how ubiquitously expressed ligands lead to a localized signal remains to be addressed. Here, we found that BMP binding protein short gastrulation (Sog) is highly expressed in the intervein cells. Our data also reveal that BMP type I receptors thickveins (Tkv) and saxophone (Sax) are highly expressed in intervein cells and at lower levels in the vein progenitor cells. RNAi knockdown of Ar-tkv or Ar-sax indicates that both receptors are required for localized BMP signaling in the wing vein progenitor cells. Taken together, our data suggest that spatial transcription of core- and co-factors of the BMP pathway sustain localized BMP signaling during sawfly wing vein development. (C) 2018 Elsevier Ltd. All rights reserved.