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ispartof: CHEMOECOLOGY vol:32 issue:4-5 pages:171-180 status: published

Complex problems in evolutionary biology can be approached in two ways, top down using theoretical constructs and bottom up using empirical studies . Theoretical concepts predominate evolutionary interpretations of eusociality in a literature that is small relative to an enormous literature of natural history and basic research that is not synthesized into a conceptual whole. Here, I draw insights from this literature to show how paper wasps’ allomaternal non-reproductive worker phenotype originates in every colony cycle via confluence of multiple factors of paper wasp biology. These include behavior, development, nutrient dynamics, indirect genetic effects, sex ratio, and demography. A novel perspective on the colony cycle, based on individuals’ reproductive physiology, serves as context to examine of each of these. It will be shown that the allomaternal non-reproductive worker phenotype does not require relatedness among colony members to originate. Allomaternal care of non-relatives is frequent and can occur in at least twelve contexts. Life histories of living species as they will be presented here show that relatedness among colony members is not the target of selection in simple eusociality. However, the novel allomaternal non-reproductive worker phenotype had to be present at the ancestral origins of complex eusociality in which relatedness among colony members is essential.

Phenotypic plasticity, the ability to produce multiple phenotypes from a single genotype, represents an excellent model with which to examine the relationship between gene expression and phenotypes. Analyses of the molecular foundations of phenotypic plasticity are challenging, however, especially in the case of complex social phenotypes. Here we apply a machine learning approach to tackle this challenge by analyzing individual-level gene expression profiles of Polistes dominula paper wasps following the loss of a queen. We find that caste-associated gene expression profiles respond strongly to queen loss, and that this change is partly explained by attributes such as age but occurs even in individuals that appear phenotypically unaffected. These results demonstrate that large changes in gene expression may occur in the absence of outwardly detectable phenotypic changes, resulting here in a socially mediated de-differentiation of individuals at the transcriptomic level but not at the levels of ovarian development or behavior., Connecting genotypes to complex social behaviour is challenging. Taylor et al. use machine learning to show a strong response of caste-associated gene expression to queen loss, wherein individual wasp’s expression profiles become intermediate between queen and worker states, even in the absence of behavioural changes.

The yellow paper wasp, Polistes versicolor (Olivier) was first recorded in the Galapagos archipelago in 1988. Its life cycle and ecological impacts were studied on two islands 11 yr after it was first discovered. This invasive wasp adapted quickly and was found in most environments. Colony counts and adult wasp monitoring showed a strong preference for drier habitats. Nest activities were seasonally synchronized, nest building followed the rains in the hot season (typically January–May), when insect prey increases, and peaked as temperature and rains started to decline. Next, the number of adult wasps peaked during the cool season when there is barely any rain in the drier zones. In Galapagos, almost half of the prey loads of P. versicolor were lepidopteran larvae, but wasps also carried spiders, beetles, and flies back to the colonies. An estimated average of 329 mg of fresh insect prey was consumed per day for an average colony of 120–150 wasp larvae. The wasps preyed upon native and introduced insects, but likely also affect insectivorous vertebrates as competitors for food. Wasps may also compete with native pollinators as they regularly visited flowers to collect nectar, and have been recorded visiting at least 93 plant species in Galapagos, including 66 endemic and native plants. Colonies were attacked by a predatory moth, Taygete sphecophila (Meyrick) (Lepidoptera: Autostichidae), but colony development was not arrested. High wasp numbers also affect the activities of residents and tourists. A management program for this invasive species in the archipelago is essential.

Reproductive conflicts are expected in societies where nonbreeding helpers retain the ability to produce offspring. Despite potential competition from reproductively capable nestmates in social wasps, egg laying tends to be monopolised by a single or relatively few queens. Genetic studies on reproductive partitioning in Polistes paper wasps suggest high reproductive skew in the genus. Conflict is thought to be minimal due to nestmate relatedness or the possibility of inheriting a reproductive monopoly on a nest; consequently, there are inclusive fitness opportunities for nonreproductive helpers. However, most studies are limited to temperate wasp species. Given the cosmopolitan distribution of Polistes, genetic data on group conflicts are required for a broader range of tropical species to determine whether these trends apply across climatic zones. We examined female reproductive skew in the Neotropical paper wasp Polistes lanio, genotyping a selection of adults and pupae from established post-emergence nests using single-nucleotide polymorphisms (SNPs). SNP-based pedigree analyses indicate a reproductive monopoly held by a single queen, with queen replacement from natal nestmates and evidence of possible multiple mating. Relatedness between pupal offspring was high (r = 0.71). It is likely that high reproductive skew among females is a founding trait of Polistes societies, conserved among species that have spread into new environments from Indomalayan origins.

Invasive species can be particularly disruptive when they intersect with organisms of conservation concern. Stabilizing the declining eastern migratory population of monarch butterflies (Danaus plexippus) is projected to require extensive habitat restoration across multiple land use sectors including metropolitan areas. Numerous conservation programs encourage urban citizens to plant gardens with milkweeds, the obligate larval host plants of the monarch. Here, we show that predation by Polistes dominula, an invasive paper wasp that is particularly abundant in urban settings, can turn such sites into ecological traps for monarch larvae. Polistes dominula was the predominant paper wasp seen foraging in central Kentucky pollinator gardens. In 120 observed encounters with monarch larvae on milkweeds in gardens, most second to fourth instars were killed, whereas most fifth instars escaped by thrashing or dropping. The wasps bit and carried off second instars whole, whereas third and fourth instar kills were first gutted, then processed and carried away piecemeal. Predation on sentinel larvae was much higher in urban gardens than in rural settings. The wasps exploited ornamental butterfly “hibernation boxes” in pollinator gardens as nesting habitat. Polistes dominula is an under-recognized predator that may diminish the urban sector’s contributions to monarch habitat restoration.

Relatively little is known about the processes shaping population structure in cooperatively breeding insect species, despite the long-hypothesized importance of population structure in shaping patterns of cooperative breeding. Polistes paper wasps are primitively eusocial insects, with a cooperative breeding system in which females often found nests in cooperative associations. Prior mark-recapture studies of Polistes have documented extreme female philopatry, although genetic studies frequently fail to detect the strong population structure expected for highly philopatric species. Together these findings have led to lack of consensus on the degree of dispersal and population structure in these species. This study assessed population structure of female Polistes fuscatus wasps at three scales: within a single site, throughout Central New York, and across the Northeastern United States. Patterns of spatial genetic clustering and isolation by distance were observed in nuclear and mitochondrial genomes at the continental scale. Remarkably, population structure was evident even at fine spatial scales within a single collection site. However, P. fuscatus had low levels of genetic differentiation across long distances. These results suggest that P. fuscatus wasps may employ multiple dispersal strategies, including extreme natal philopatry as well as longer-distance dispersal. We observed greater genetic differentiation in mitochondrial genes than in the nuclear genome, indicative of increased dispersal distances in males. Our findings support the hypothesis that limited female dispersal contributes toward population structure in paper wasps.

Why workers forfeit direct reproduction is a crucial question in eusocial evolution. Worker reproduction provides an excellent opportunity to understand the mechanism of kin conflict resolution between the queen and workers. We evaluated behavioral and physiological differences among females in the paper wasp Polistes chinensis antennalis to examine why some workers reproduce under queenright conditions. Reproductive workers were old and foraged less early in the season; their cuticular hydrocarbon (CHC) profiles overlapped with those of queens but were significantly different. The distinct CHC profile of the eggs of the queen likely represented a cue for policing against those by workers. Juvenile hormone (JH) and dopamine seemed to be associated with gonadotropic function, and the JH level of reproductive workers was similar to that of the queen. The high JH level of reproductive workers likely facilitated their reproduction even under queenright conditions. Gene expression levels of the queen and reproductive workers differed only in vitellogenin. These results suggest that worker reproduction is facilitated by an increase in JH level; however, CHC is not a fertility-linked signal, but a queen-linked signal; consequently, reproductive workers without a queen-linked signal might be allowed to stay within the colony.

Visual individual recognition requires animals to distinguish among conspecifics based on appearance. Though visual individual recognition has been reported in a range of taxa, the features that animals rely on to discriminate between individuals are often not well understood. Northern paper wasp females, Polistes fuscatus, possess individually distinctive color patterns on their faces, which mediate individual recognition. It is currently unclear what facial features P. fuscatus use to distinguish individuals. The anterior optic tubercle, a chromatic processing brain region, is especially sensitive to social experience during development, suggesting that color may be important for recognition in this species. We sought to test the roles of color in wasp facial recognition. Color may be important simply because it creates a pattern. If this is the case, then wasps should perform similarly when discriminating color or grayscale images of the same faces. Alternatively, color itself may be important for recognition, which would predict poorer performance on grayscale image discrimination relative to color images. We found wasps trained on grayscale faces, unlike those trained on color images, did not perform better than chance. Suggesting that color is necessary for the recognition of an image as a face by the wasp visual system.

The ability to recognize and discriminate among others is a frequent assumption of models of the evolution of cooperative behavior. At the same time, cooperative behavior has been proposed as a selective agent favoring the evolution of individual recognition abilities. While theory predicts that recognition and cooperation may co-evolve, data linking recognition abilities and cooperative behavior with fitness or evidence of selection are elusive. Here, we provide evidence of a fitness link between individual recognition and cooperation in the paper wasp Polistes fuscatus. Nest founding females in northern populations frequently form cooperative multiple foundress nests and possess highly variable facial patterns that mediate individual recognition. We describe a dearth of cooperative nesting, low phenotypic diversity, and a lack of individual recognition in southern populations. In a common garden experiment, northern co-foundress associations successfully reared offspring while all cooperative southern groups failed to rear any offspring, suggesting a fitness link between individual recognition and successful cooperation. Consistent with a selective link between individual recognition and cooperation, we find that rates of cooperative co-nesting correlate with identity-signaling color pattern diversity across the species’ range. Moreover, genomic evidence of recent positive selection on cognition loci likely to mediate individual recognition is substantially stronger in northern compared to southern P. fuscatus populations. Collectively, these data suggest that individual recognition and cooperative nesting behavior have co-evolved in P. fuscatus because recognition helps mediate conflict among co-nesting foundresses. This work provides evidence of a specific cognitive phenotype under selection because of social interactions, supporting the idea that social behavior can be a key driver of cognitive evolution.

An exceptionally bright fluorescent biomatter was discovered when exploring, with UV-A light, the nests of several oriental paper wasp species of the genusPolistes, a genus of diurnal social insects. Fluorescence spectra of the cocoon cap membranes revealed narrow emission bands in the green range of the visible spectrum. Large Stokes shifts of around 160 nm and high fluorescence quantum yields of up to 35% were measured. Transmission spectra were recorded in order to estimate the contribution of the fluorescence to the visible light transmitted through the cocoon cap membrane. The nest fluorescence of the Vietnamese wasps was compared with a European and an American species. Potential biological functions of these interesting fluorescence properties of the studied biomaterial are discussed. The discovery of this striking example of a fluorescent terrestrial biomaterial may contribute to the debate on adaptive biological functions of natural fluorescence and falls in line with the growing interest in biodiversity and bio-inspiration.

Social wasps are considered among the most successful and impactful invasive species in the world. One species, Polistes dominula has spread from its native Mediterranean range to every continent except Antarctica. This wasp reached New Zealand in the last decade where it has established in the north of the South Island, however, reports of its presence are increasing throughout the country. Due to its recent arrival in New Zealand, little is known about where this species is likely to establish or what impacts it may have on local insect communities. In this thesis, I conducted two studies to investigate these questions, providing valuable information that may inform future management of this invasive species. In chapter 2, I used two bioclimatic modelling methods to predict areas of suitable habitat across four regions in the southern hemisphere. These models were informed by global temperature and precipitation data as well as global distribution occurrence data of P. dominula. These data were used to estimate conditions most highly correlated with the presence of this wasp. The models identified large areas across the target regions that were climatically suitable for the establishment of P. dominula. Many of these areas are not known to currently contain populations of this species, representing habitat potentially vulnerable to further invasion by P. dominula. Areas across South America, South Africa and Australia were predicted to be climatically suitable. In New Zealand, much of the North Island and eastern parts of the South Island were predicted to be suitable habitat for this wasp. These results suggest that P. dominula could potentially establish across more of the country and expand its invaded range. Information provided by these models may guide conservation and biosecurity management by highlighting key areas where prevention and mitigation should be prioritized. In chapter 3, I used molecular diet analysis to investigate the range of prey being utilised by P. dominula in New Zealand. Using DNA barcoding, larval gut contents of P. dominula and another closely related species, Polistes chinensis, were analysed to identify what species were present in the diet of both wasps. Butterflies and moths (Lepidoptera) were found to be the most highly represented order in both species’ diets. True bugs (Hemiptera) and flies (Diptera) were also abundant. Both wasps were shown to consume a range of native and introduced species including a number of agricultural pests. P. dominula was found to utilise a wider range of prey than P. chinensis. This more diverse prey range, combined with known differences in nesting behaviour, suggest that P. dominula may represent a more significant threat to invertebrate diversity than the already well-established P. chinensis. These results may inform conservation and biosecurity managers on which species are most at risk where this new invasive wasp becomes established. This thesis provides insights into the potential impacts of a new invasive species to New Zealand. Both chapters represent the first time that these methods have been used to study P. dominula. This work highlights the need for continued monitoring of wasp populations throughout New Zealand, especially in regions highlighted as vulnerable to P. dominula establishment. We also suggest the need to prioritise the conservation of ‘at-risk’ species in coastal and human-altered habitats. Increased public engagement through the citizen-science initiatives should be encouraged while more research into management and control methods is recommended.

Stable social groups usually consist of families. However, recent studies have revealed higher level social structure, with interactions between family groups across different levels of social organization in multiple species. The explanations for why this apparently paradoxical behaviour arises appear to be varied and remain untested. Here, we use automated radio-tagging data from over 1000 wasps from 93 nests and social network analyses of over 30 000 nest visitation records to describe and explain interactions across levels of social organization in the eusocial paper wasp Polistes canadensis . We detected three levels of social organization (nest, aggregation and community) which exchange ‘drifter’ individuals within and between levels. The highest level (community) may be influenced by the patchiness of high-quality nesting habitats in which these insects exist. Networks of drifter movements were explained by the distance between nests, the group size of donor nests and the worker-to-brood ratios on donor and recipient nests. These findings provide some explanation for the multi-level social interactions, which may otherwise seem paradoxical. Fitness benefits across multiple levels of social organization should be considered when trying to understand animal societies.

Introduced wasps can have significant impacts on communities within their newly invaded range. A recent wasp introduction to New Zealand is the European paper wasp, Polistes dominula Christ, which was first observed in the Nelson-Tasman region in 2016. The ecology and behaviour of P. dominula was investigated, as well as the direct and indirect impacts of this wasp on local communities in Nelson. Aspects of nesting behaviour, habitat preference and abundance were studied with the intent to inform management decisions. The abundance and colony survival of P. dominula was greatest in suburban areas, where nests were predominantly built within anthropogenic structures. Colony survival of P. dominula was comparatively higher than for colonies of the longer established exotic congener Polistes chinensis Pérez. Neither Polistes species were found to nest within native or exotic forest sites, with translocated colonies of P. dominula unsuccessful within forest habitats. As a species that originates from a warmer climate, the lower temperatures in forests are likely a contributor to the inability of P. dominula to thrive in these areas. The impacts that newly invasive predators have on communities within their invaded range are often poorly understood. Following the arrival of P. dominula, I show data indicating that there have been substantial declines in the abundance of several local butterfly species in Nelson. The monarch butterfly, Danaus plexippus Linnaeus was one of the species reported by residents to be in population decline. Field experiments found P. dominula to be a major cause of monarch caterpillar mortality. Caterpillar survival was the lowest in suburban areas, where the abundance of P. dominula was highest. Early instar caterpillars had comparatively higher mortality rates than late instar caterpillars, as the defensive behaviour of larger caterpillars had greater success against these wasps. Whilst P. dominula was the main driver behind caterpillar mortality throughout my experiments, the discovery of caterpillars by wasps appeared to happen by chance through direct contact between the wasp and their prey. There was also no evidence of nestmate recruitment by foraging wasps to sites where caterpillars were found. Predation has the capacity to not only impact prey populations, but through the suppression of herbivory, plants can indirectly benefit from the presence of predators. The presence of P. dominula was found to have strong, cascading effects on the milkweed host and food plant of D. plexippus. Milkweed fitness in areas populated by P. dominula was substantially greater than the fitness of plants in areas without this invasive predator. Plant growth and reproduction of milkweeds placed in areas where P. dominula were present, and able to predate upon caterpillars, were found to exhibit a similar amount of growth and flower production as netted control plants which excluded monarch caterpillars completely. The outcomes of this experiment suggest that P. dominula is strongly suppressing these herbivorous caterpillars. Overall, this thesis provides insight into the behaviour and ecology of P. dominula in New Zealand. Findings of this research suggest that this newly invasive wasp is having detrimental effects on local communities and that P. dominula should be controlled to reduce the impacts of this wasp on New Zealand’s ecosystems. Knowledge obtained in this study can direct conservation management strategies and aid in the development of effective control methods.

Developmental studies of brain volumes can reveal which portions of neural circuits are sensitive to environmental inputs. In social insects, differences in relative investment across brain regions emerge as behavioural repertoires change during ontogeny or as a result of experience. Here, we test the effects of maturation and social experience on morphological brain development inPolistes fuscatuspaper wasps,focusing on brain regions involved in visual and olfactory processing. We find that mature wasps regardless of social experience have relatively larger brains than newly emerged wasps and this difference is driven by changes to mushroom body calyx and visual regions but not olfactory processing neuropils. Notably, social wasps invest more in the anterior optic tubercle (AOT), a visual glomerulus involved in colour and object processing in other taxa, relative to other visual integration centres the mushroom body calyces compared with aged socially naive wasps. Differences in developmental plasticity between visual and olfactory neuropil volumes are discussed in light of behavioural maturation in paper wasps, especially as it relates to social recognition. Previous research has shown thatP. fuscatusneed social experience to develop specialized visual processing of faces, which is used to individually recognize conspecifics. The present study suggests that the AOT is a candidate brain region that could mediate facial processing in this species.

The social paper wasp Agelaia pallipes is known to eat carrion and scavenge on vertebrates. There are few records of wasps predating vertebrates, including an attack on an adult hummingbird and the predation of bird nestlings. During a project monitoring reproductive behaviour of a neotropical songbird, the Lined Seedeater Sporophila lineola in south-eastern Brazil, we recorded the predation of a four-day-old nestling by a social paper wasp. In the video, the adult female bird attempted to visit the nest prior to the predation. The male could be seen with its crest feathers erect after a wasp left the nest, when the nestling was presumably already dead. When we arrived at the nest to remove the camera, we found the nestling dead, and did not observe the parents in the vicinity. We also registered two other dead nestlings in a different nest with similar wounds. However, the conclusive cause of death of those nestlings is unknown. Nest predation is a major selective pressure in birds, and insects are rarely assumed to play a notable role in this process. Further research is needed to better understand the nature of the relationship between wasps and birds.

Purpose Many treatments, such as conservative management or penetrating keratoplasty, exist for corneal wasp sting. Here, we report a case of paper wasp sting of the cornea treated by anterior chamber wash immediately following admission, which soon resolved the inflammation. Case A healthy 9-year-old boy who had been stung by a paper wasp on his left eye 2 days prior to presentation at Dokkyo Medical University Saitama Medical Center was found to have corneal opacity accompanied by ciliary injection. The boy had difficulty opening his left eye due to pain. His left corneal endothelial cell density was 2,789 cells/mm2, which was relatively lesser than that in the right eye. We diagnosed a paper wasp sting of the cornea based on both the patient's clinical findings and sting history. The anterior chamber was promptly irrigated using a balanced salt solution; the inflammation resolved in a few hours, and the patient could open his left eye easily the following day. One day after the operation, the visual acuity improved to 1.2, and only slight corneal opacity remained at the original wasp sting site. Conclusion The positive outcome of the current case suggested that anterior chamber irrigation leads to rapid resolution of the inflammation.

Obligate social parasites evolve traits to effectively locate and then exploit their hosts, whereas hosts have complex social behavioral repertoires, which include sensory recognition to reject potential conspecific intruders and heterospecific parasites. While social parasite and host behaviors have been studied extensively, less is known about how their sensory systems function to meet their specific selective pressures. Here, we compare investment in visual and olfactory brain regions in the paper wasp Polistes dominula, and its obligate social parasite P. sulcifer, to explore the link between sensory systems and brain plasticity. Our results show opposite and significant differences, consistent with their very different life-histories, in the sensory investments between these two closely-related species. Social parasites initially invest in the optic lobes to likely locate their hosts. After host colony usurpation, the parasite increases its brain volume, with specific investment in antennal lobes, which mirrors the behavioral switch from a usurping parasite to an integrated parasitic queen of the host colony. Contrastingly, hosts initially invest in the antennal lobes and sensory processing compared to social parasites, as predicted by their need to maintain social cohesion, allocate colony tasks, and recognize con- and heterospecific intruders. Host queens show a trend of higher investment in all sensory brain regions compared to workers, paralleling differences in task allocations. Our work provides novel insights into how intraspecific brain plasticity can facilitate the unique sensory adaptations needed to perform specific tasks by the host or to transition from searching to successful host exploitation by the social parasite.

We examined the abundance, nesting ecology, and colony survival of two invasive species of paper wasp, Polistes dominula Christ (Hymenoptera: Vespidae) and Polistes chinensis Pérez (Hymenoptera: Vespidae), within their invaded range in New Zealand. The more recent invader, P. dominula, exhibited a strong habitat preference, reaching the highest abundances within suburban areas with an average of 87.4 wasps per 1,000 m2. Coastal habitats were also found to be suitable environments for P. dominula, although wasp abundance in these areas was comparatively lower than suburban sites at 26.5 wasps per 1,000 m2. Although P. chinensis were observed to build more nests in coastal habitats, this was not reflected in the abundance of adult wasps in these areas. Nests of P. dominula were larger and more productive, likely a result of the multiple founding and earlier emergence of workers compared to P. chinensis. Both species exhibited significant differences in nest survival, with P. dominula observed to have a higher colony survival rate, particularly in suburban habitats where this species utilized man-made substrates as nesting sites. Neither species nested within forest sites and translocated nests of P. dominula failed to thrive within forest habitats. Findings of this research suggest that P. dominula will not pose a threat to species inhabiting forested areas. Instead, biodiversity managers should focus their efforts on suburban and coastal environments as native species in these areas will require the greatest protection.

Independent origins of sociality in bees and ants are associated with independent expansions of particular odorant receptor (OR) gene subfamilies. In ants, one clade within the OR gene family, the 9-exon subfamily, has dramatically expanded. These receptors detect cuticular hydrocarbons (CHCs), key social signaling molecules in insects. It is unclear to what extent 9-exon OR subfamily expansion is associated with the independent evolution of sociality across Hymenoptera, warranting studies of taxa with independently derived social behavior. Here we describe odorant receptor gene family evolution in the northern paper wasp, Polistes fuscatus, and compare it to four additional paper wasp species spanning ~40 million years of divergence. We find 200 functional OR genes in P. fuscatus matching predictions from neuroanatomy, and more than half of these are in the 9-exon subfamily. Lineage-specific expansions of 9-exon subfamily ORs are tandemly arrayed in Polistes genomes and exhibit a breakdown in microsynteny relative to tandem arrays in other OR subfamilies. There is evidence of episodic positive diversifying selection shaping ORs in expanded subfamilies, including 9-exon, E, H, and L, but 9-exon ORs do not stand out as selectively diversified among Polistes species. Accelerated evolution has resulted in lower amino acid similarity and high dN/dS among 9-exon ORs compared to other OR subfamilies. Patterns of OR evolution within Polistes are consistent with 9-exon OR function in CHC perception by combinatorial coding, with both selection and drift contributing to interspecies differences in copy number and sequence.

The dominance-nutrition hypothesis predicts that nutritional intake and energetic costs in adulthood interact to drive behavioral and physiological differences between females in primitively eusocial insects, and thereby affect reproductive caste. We tested predictions of this hypothesis in independent-founding Mischocyttarus pallidipectus paper wasps. We measured stable isotope tissue composition to compare nutritional status before adult emergence and among adult females. Adult tissue δ15N content (an indicator of feeding at a higher trophic level because it is enriched in animal prey relative to plant-based foods) was significantly higher in adults than at the end of pupal development, suggesting adult nutrition affects δ15N content after the end of pupal development. We then asked if behavior and nutritional status predicted ovary development. We measured ovary development, nitrogen and carbon stable isotope ratios, dominance behavior, and task performance (foraging, as indicated by time spent on the nest) for adult female wasps. We used social network analysis to quantify differences in social status between females with developed and undeveloped (filamentous) ovaries. Dominant females spent more time on the nest and were significantly more enriched in δ15N than subordinate females. These data support the dominance-nutrition hypothesis: adult behavior and energy expenditure, and access to animal-based diets, correspond to female reproductive physiology, and may play a role in adult-stage caste determination. Within animal social groups, differential access to resources can affect differences in reproductive success. This may affect caste determination in eusocial colonies, where reproductive tasks are divided between female castes, with a queen (or multiple queens) capable of egg-laying and helped by sterile workers. Female sterile workers and reproductives of some social Hymenoptera are morphologically similar at adult emergence, suggesting that adult experience may impact caste status. We asked whether patterns of nutritional physiology in Mischocyttarus pallidipectus paper wasps matched adult-stage caste determination by testing predictions of the dominance-nutrition hypothesis, which states that adult nutrition and energetic costs of tasks shape reproductive female development through behavioral and physiological changes.

Refurbishing the old nest in order to prepare it for a new breeding season cycle has already been observed in few species of paper wasps. When future foundresses emerge from hibernacula they have choose between building a new nest or reusing an old one. In present paper I described a case of multiple use and further expansion an old nest by Polistes dominula (Christ, 1791) in Grodzisk Mazowiecki, Mazovia Region, Central Poland.

Phenotypic plasticity, the ability to produce multiple phenotypes from a single genotype, represents an excellent model with which to examine the relationship between gene expression and phenotypes. Despite this, analyses of the molecular bases of plasticity have been limited by the challenges of linking individual phenotypes with individual-level gene expression profiles, especially in the case of complex social phenotypes. Here, we tackle this challenge by analysing the individual-level gene expression profiles of Polistes dominula paper wasps following the loss of a queen, a perturbation that induces some individuals to undergo a significant phenotypic shift and become replacement reproductives. Using a machine learning approach, we find a strong response of caste-associated gene expression to queen loss, wherein individuals’ expression profiles become intermediate between queen and worker states. Importantly, this change occurs even in individuals that appear phenotypically unaffected. Part of this response is explained by individual attributes, most prominently age. These results demonstrate that large changes in gene expression may occur in the absence of detectable phenotypic changes, resulting here in a socially mediated de-differentiation of individuals at the transcriptomic but not the phenotypic level. Our findings also highlight the complexity of the relationship between gene expression and phenotype, where transcriptomes are neither a direct reflection of the genotype nor a proxy for the molecular underpinnings of the external phenotype.

Made available in DSpace on 2020-12-10T20:09:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Females of many social Hymenoptera commit their reproductive potential to a single male; they mate once and never re-mate. Sexual selection theory predicts that under this regimen female precopulatory mate choice is crucial. The targets of female choice, male secondary sexual traits, should convey information about the functional fertility of the male. Here, we evaluated semen quality and its correlates in the paper wasp Polistes dominula, a monandric species with a lek-based mating system. The main goal of the study was to test whether sperm viability and the total number of sperm covaried with sexually dimorphic abdominal spots, body size and parasitic infection by Xenos vesparum. Surprisingly, superior male fertility was not predicted by attractive sexual traits, such as little round spots and large body size. We also found no effect of the parasite on male fertility, sexual ornamentation or body size. We found only that sperm viability was positively associated with the number of sperm. Moreover, there was evidence of a counterintuitive relationship between (sexually unattractive) large irregular spots and large body size of dominant successful males. Overall, our results suggest a condition-dependent trade-off between body size and costly sexual signals. Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, Sao Paulo, Brazil Univ Estadual Paulista, Inst Biociencias Letras & Ciencias Exatas, Dept Zool & Bot, Sao Jose Do Rio Preto, Brazil Univ Florence, Dept Biol, Florence, Italy Univ Fed Vicosa, Dept Biol Geral, Vicosa, MG, Brazil Univ Estadual Paulista, Inst Biociencias Letras & Ciencias Exatas, Dept Zool & Bot, Sao Jose Do Rio Preto, Brazil FAPESP: 16/18254-7

Made available in DSpace on 2020-12-12T01:37:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Mischocyttarus cerberus stands out as the most investigated species of eusocial paper wasp, in Brazil. While the adult characteristics were relatively well reported in the earlier studies, very meager information was available regarding their immature stages. This study provides a general description of the immature morphology of the brood of M. cerberus, by studying the number of instars and analyzing the degree of influence exerted by some of the environmental factors on the individuals in the immature phases. This work involves a detailed study of 72 wasp colonies from Rio Claro and Ribeirão Preto. Using the larvae drawn from 41 nests, the number of instars was calculated; besides, the degree to which a few environmental factors could affect the immature brood development was assessed in 31 nests. Eggs showed patterns similar in terms of form and size to that of the species described earlier. The two ventral lobes, characteristic of the Mischocyttarus larvae, were fully developed only in the fifth instar. Based on the head measurements, we found that M. cerberus also express five larval instars, which is in agreement with reports published earlier for the most part of social wasps. Besides, larvae took longer than eggs and pupae to develop. From the results of our study, we concluded that M. cerberus showed the typical developmental pattern in the immature stages of the genus. Universidade de São Paulo (USP) Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Departamento de Biologia Universidade Estadual Paulista (Unesp) Instituto de Biociências Departamento de Zoologia Universidade Estadual Paulista (Unesp) Instituto de Biociências Departamento de Zoologia

Allergic reactions to stings of Hymenoptera species can have serious or even fatal consequences. If the identification of the culprit insect is possible, venom-specific immunotherapy effectively cures Hymenoptera venom allergies. Although component-resolved diagnostics has strongly evolved in recent years, the differentiation between allergies to closely related species such as Polistes dominula and Vespula spp. is still challenging. In order to generate the basis for new diagnostic and therapeutic strategies, this study aims at resolving the venom proteomes (venomes) of these species. The venoms of P. dominula and Vespula spp. (V. germanica, V. vulgaris) were analyzed by liquid chromatography-mass spectrometry. Resulting proteins were characterized regarding their function, localization and biochemical properties. The analyses yielded 157 proteins in Vespula spp. and 100 in P. dominula venom, 48 proteins, including annotated allergens, were found in both samples. In addition to a variety of venom trace molecules, new allergen candidates such as icarapin-like protein and phospholipase A2 were identified. This study elucidates the venomes of closely related allergy-eliciting Hymenoptera species. The data indicates that relying on marker allergens to differentiate between P. dominula and Vespula spp. venom allergy is probably insufficient and that strategies using cross-reactive major allergens could be more promising.

Cognitive abilities can vary dramatically among species. The relative importance of social and ecological challenges in shaping cognitive evolution has been the subject of a long-running and recently renewed debate, but little work has sought to understand the selective dynamics underlying the evolution of cognitive abilities. Here, we investigate recent selection related to cognition in the paper wasp Polistes fuscatus —a wasp that has uniquely evolved visual individual recognition abilities. We generate high quality de novo genome assemblies and population genomic resources for multiple species of paper wasps and use a population genomic framework to interrogate the probable mode and tempo of cognitive evolution. Recent, strong, hard selective sweeps in P. fuscatus contain loci annotated with functions in long-term memory formation, mushroom body development, and visual processing, traits which have recently evolved in association with individual recognition. The homologous pathways are not under selection in closely related wasps that lack individual recognition. Indeed, the prevalence of candidate cognition loci within the strongest selective sweeps suggests that the evolution of cognitive abilities has been among the strongest selection pressures in P. fuscatus ’ recent evolutionary history. Detailed analyses of selective sweeps containing candidate cognition loci reveal multiple cases of hard selective sweeps within the last few thousand years on de novo mutations, mainly in noncoding regions. These data provide unprecedented insight into some of the processes by which cognition evolves.

Sex-biased dispersal is common in social species, but the dispersing sex may delay emigration if associated benefits are not immediately attainable. In the social Hymenoptera (ants, some bees and wasps), newly emerged males typically disperse from the natal nest whilst most females remain as philopatric helpers. However, little information exists on the mechanisms regulating male dispersal. Furthermore, the conservation of such mechanisms across the Hymenoptera and any role of sexual maturation are also relatively unknown. Through field observations and mark–recapture, we observed that males of the social paper wasp Polistes lanio emerge from pupation sexually immature, and delay dispersal from their natal nest for up to 7 days whilst undergoing sexual maturation. Delayed dispersal may benefit males by allowing them to mature in the safety of the nest and thus be more competitive in mating. We also demonstrate that both male dispersal and maturation are associated with juvenile hormone (JH), a key regulator of insect reproductive physiology and behaviour, which also has derived functions regulating social organisation in female Hymenoptera. Males treated with methoprene (a JH analogue) dispersed earlier and possessed significantly larger accessory glands than their age-matched controls. These results highlight the wide role of JH in social hymenopteran behaviour, with parallel ancestral functions in males and females, and raise new questions on the nature of selection for sex-biased dispersal.

In the present work we report the first occurrence of the entomogenous fungus Hirsutella saussurei, in the Galápagos Islands, and also the first evidence of this fungus parasitizing a new host: the invasive paper wasp Polistes versicolor. Some wasps parasitized by the fungus were found in Santa Cruz island in 2018 and 2019, while two new specimens were found in Floreana in 2019. Our data enlarge both the geographical distribution of the fungus and the host range. Even though P. versicolor is considered an important threat for the Galapagos endemic fauna, it is necessary a deep research to know if H. saussurei could be included under control programs of this invasive wasp.