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The Parque Nacional Grande Sertão Veredas, northern Minas Gerais, is located in the Cerrado, a global hotspot, and the literature lacks information about its communities of social wasps, insects that perform numerous services for the functioning of ecosystems. Therefore, this study aimed to conduct an inventory of social wasps (Vespidae: Polistinae) in the Parque Nacional Grande Sertão Veredas, and compare its richness and composition with three other fully protected conservation units in northern Minas Gerais and Vale do Jequitinhonha, Minas Gerais. A total of 41 species of 14 genera of social wasps were recorded, including a new occurrence in the state: Mischocyttarus campestris Raw, 1985. The presence of distinct social wasp communities in the Cerrado and Caatinga conservation units analyzed in this study, reinforces and justifies the creation of these fully protected areas, which ensure the conservation of this biological heritage and the environmental services provided by these taxa, besides providing subsidies for the management and sustainable use of the natural resources of these conservation units. [ABSTRACT FROM AUTHOR]

Optimal foraging theory predicts that well‐defended potential foods should be exploited only when energy pay‐offs are great. Although stinging hymenopteran nests are both well‐defended and predated by primates, their larvae's energy yields rarely have been calculated, and predation‐linked foraging behaviours by primates infrequently documented. Based on 58 opportunistic observations of primates raiding wasp nests for larvae, we calculated energetic yields of low‐ and high‐risk wasp nest predation for Cebus albifrons, Saimiri collinsi, S. sciureus and Sapajus apella, and tested predictions derived from optimal foraging theory. We recorded how nests were processed and by which age‐sex classes, eaten nest fragment sizes, number of occupied and empty cells, and nest occupancy patterns (percent larvae/pupae, eggs, empty cells). Basal metabolic rate (BMR) calculations showed energetic yields from 15 min foraging on low‐risk nests (Polybia quadricincta) would meet energy needed to sustain adult female and male C. albifrons BMR for 4.9 and 4.5 h, respectively; yields from high‐risk (Chartergus artifex) nests for 6.5 and 6.2 h; Mischocyttarus sp. nest yields (low risk, but mimetically resembling other wasps) would meet S. collinsi BMR for 2.9 h (female) and 2.3 h (male), and 2.6 and 2.1 h, for the slightly larger S. sciureus, respectively. The Chartergus energetic‐yield value is nearly 20% of a 36 g chocolate bar (741 kJ). Our data provide quantitative support for the common assertion that wasp larvae and pupae are high‐yield foods for primates. As predicted by optimal foraging, energetic yield is sufficient to offset the risk and pain of being stung. [ABSTRACT FROM AUTHOR]

During social interactions, the behavior of an individual often depends on the sex of its social partner. Many animal societies have males and females that play very different behavioral roles, although they coexist and interact non-sexually. At specific phases of the colony cycle, social wasp females and males are contemporaries within a nest, they often interact, although mating occurs mostly off the nest, therefore providing an opportunity to test sex discrimination in contexts other than classical sexual ones. We performed a lure presentation experiment to test if Mischocyttarus metathoracicus discriminate between conspecifics of the 2 sexes during on-nest social interactions. Female wasps discriminated conspecific sex during experimentally simulated nest intrusions. Visual and chemical cues may account for this sex discrimination. Despite sex discrimination (evidenced by differential inspective behavior from the nest females toward the female and the male lures), female wasps were as aggressive toward lures of both sexes. In the female-dominated hymenopteran societies, males are often subordinate and not aggressive on nest, resulting in females directing less aggression to them compared to other females. Instead, M. metathoracicus males and females are both aggressive toward nestmates, so they might be perceived as similar threat during on-nest social interactions. [ABSTRACT FROM AUTHOR]

Host immune activation is common under a pathogen invasion. This physiological response can promote changes in the body surface compounds, thus providing chemical cues related to health that might be useful to conspecifics. By recognizing the current immunological status of social partners, individuals can modulate their behavior to minimize the risk of infection. Tegument wounding, an immune elicitor, is a required step for many parasites to become established in a host. By using the neotropical eusocial paper wasp Mischocyttarus metathoracicus as a model organism, we first performed a lure presentation experiment in the field to test if wasps discriminate conspecific immunological status (experimentally manipulated by wounding) during on nest social interactions. Then, we performed gas chromatography–mass spectrometry analyses to test if immunostimulation by wounding alters the wasps' cuticular hydrocarbon profile. We found that wasps reduce the duration of aggressive physical contact when interacting with wounded lures, despite displaying a similar frequency of inspective and aggressive behaviors toward both the wounded and the control lures. Besides, we found a subtle increase in a single cuticular hydrocarbon in the wounded wasps. Thus, wasps recognize conspecific immunological status, likely by chemical cues, and modulate their behavior in order to defend the colony against intruders while minimizing the personal risk of infection. [ABSTRACT FROM AUTHOR]

Cooperative breeding decreases the direct reproductive output of subordinate individuals, but cooperation can be evolutionarily favored when there are challenges or constraints to breeding independently. Environmental factors, including temperature, precipitation, latitude, high seasonality, and environmental harshness have been hypothesized to correlate with the presence of cooperative breeding. However, to test the relationship between cooperation and ecological constraints requires comparative data on the frequency and variation of cooperative breeding across differing environments, ideally replicated across multiple species. Paper wasps are primitively social species, forming colonies composed of reproductively active dominants and foraging subordinates. Adult female wasps, referred to as foundresses, initiate new colonies. Nests can be formed by a single solitary foundress (noncooperative) or by multiple foundress associations (cooperative). Cooperative behavior varies within and among species, making paper wasps species well suited to disentangling ecological correlates of variation in cooperative behavior. This data set reports the frequency and extent of cooperative nest founding for 87 paper wasp species. Data were assembled from more than 170 published sources, previously unpublished field observations, and photographs contributed by citizen scientists to online natural history repositories. The data set includes 25,872 nest observations and reports the cooperative behavioral decisions for 45,297 foundresses. Species names were updated to reflect modern taxonomic revisions. The type of substrate on which the nest was built is also included, when available. A smaller population-level version of this data set found that the presence or absence of cooperative nesting in paper wasps was correlated with temperature stability and environmental harshness, but these variables did not predict the extent of cooperation within species. This expanded data set contains details about individual nests and further increases the power to address the relationship between the environment and the presence and extent of cooperative breeding. Beyond the ecological drivers of cooperation, these high-resolution data will be useful for future studies examining the evolutionary consequences of variation in social behavior. This data set may be used for research or educational purposes provided that this data paper is cited.

Juvenile hormone (JH) is a key insect hormone involved in the regulation of physiological, developmental and behavioural processes. In social insects, it has been shown that JH can play a key role in modulating reproductive division of labour, age-related division of labour and chemical signalling, and can display marked changes in function of the degree of sociality. Here, we checked the effects of JH on reproduction in single foundresses of two neotropical primitively eusocial wasp species, Mischocyttarus cerberus and Mischocyttarus cassununga, by examining how treatments with the JH-analogue methoprene and the anti-JH precocene affect egg-laying, ovarian activation and chemical profiles. Our hypothesis was that reproduction and the production of particular fertility-linked cuticular hydrocarbon cues might be under shared JH control already in primitively eusocial wasp species, and this could have been a key enabler to allow such cues to later evolve into full-fledged queen pheromone signals in advanced eusocial species. In line with this hypothesis, we show that our hormone treatments significantly affected both egg laying and the production of particular hydrocarbons present on the egg surface. We discuss the relevance of these findings in the context of the evolution of social insect queen pheromones in advanced eusocial species with a morphologically differentiated queen–worker caste. [ABSTRACT FROM AUTHOR]

This study was developed aiming to compile data concerning the occurrence and distribution of social wasp species from the Brazilian Atlantic Forest, as well as recording exclusive and rare species. For this purpose, we compiled studies from the specialized literature and created a table containing the species occurrence in the different states which present the phytogeographic domain. A total of 170 species was recorded, corresponding to almost a half of the richness of social wasps in Brazil, including 50 endemic, with highlight to Rio de Janeiro state, which nevertheless is insufficiently sampled. This way, from this work, it is concluded that Brazilian Atlantic Forest must be seen as an important refuge for Polistinae.

Phylogenetic studies suggest that historically all paper wasps (Vespidae: Polistinae) in North America have tropical origins, but some species have adapted to survive temperate conditions. Subtropical climates, which are intermediate between temperate and tropical, allow a unique opportunity to study ancestral traits which can be retained or lost within populations, and ultimately elucidate the process of social wasp evolution. We investigated the phenology of paper wasps at study sites in subtropical Baton Rouge, USA, through nest searching and monitoring of nest parameters throughout the warm season (March–October). Across the year, two periods of nest initiation occurred: from March–May (early season nests, i.e., before the summer solstice), and from July–September (late season nests, after the solstice). We observed 240 Polistes nests from six species, of which 50.8% were initiated in early season and 49.2% in late season. In contrast, Mischocyttarus mexicanus rarely built late season nests and had longer early season colony duration than Polistes bellicosus and P. dorsalis, which built more nests in the late season than early. Across all species, late season nests had significantly shorter colony duration (~87.6 days) than early season nests (~166 days), and only P. bellicosus had fewer adults at peak population in late season nests than in early season nests. Results indicate both a bivoltine colony cycle in Polistes of subtropical climates, as well as differences in nesting strategies between genera.

The forest fragmentation is caused by natural or anthropic actions, which affect negatively the biota and the environmental services rendered by biological diversity. However, there is little information on the reflex of these actions in many different groups of animals, such as social wasps, which are abundant and significantly present in neotropical environments, causing a major impact in the communities they live due to their role in food webs. As their natural enemies, wasps are important in the control of agricultural plagues; in the natural environment, they are nectar collectors, frequent flower visitors, and potential pollinators of many species of plants. These factors justify studies which would evaluate in what way the forest fragmentation acts on these insects biodiversity. This study was carried out in four fragments, each of a different size, located in the municipalities of Inconfidentes and Ouro Fino, in the south of the state of Minas Gerais (Brazil), where the phytophysiognomy is the Montane Semideciduous Seasonal Forest. The research was carried out between December 2016 and March 2018, with the same sampling collection for each fragment, totalizing 104 sampling days. In total, 28 species and 51 colonies were recorded in the four areas and a greater richness for the greatest fragment (F4). The conclusion reached was that the size and heterogeneity of the fragment have an important role in maintaining the richness of social wasps.

The aim of this study was to explore whether the nest chemical profile (NCP) can be used to determine intra- and interspecific differences in social wasps of the subfamily Polistinae. For this purpose, Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) was used to directly analyze small pieces of nest as well as the gasters of females. An advantage of the methodology was that no sample preparation was required. FTIR-PAS combined with multivariate discriminant analyzes was used, to the best of our knowledge for the first time, to evaluate the NCPs of six species of polistine wasps, observing the influence of the nesting environment and investigating the relationships among the nest and female cuticular chemical profiles. The results revealed significant inter-species differences among the NCPs, as well as strong correlations with the environments in which the nests were located. The Mischocyttarus and Polistes species belong to the same tribe (Polistini) and therefore exhibited similar NCPs. These species were separated from the Polybia species in the NCP dendrogram, mainly because the Polybia belong to another tribe (Epiponini). Correlation was observed between the NCPs and the cuticular chemical profiles of females. The findings of the study demonstrated the importance of the NCP for differentiation of species and environments, and the utility of FTIR-PAS for identification of correlations between individuals and nests. The results confirmed the hypothesis that the NCP can be used as an additional tool for intra- and interspecific differentiation in social wasps of the subfamily Polistinae. [ABSTRACT FROM AUTHOR]

The life history of Chalcoela iphitalis--a common brood parasite of social wasps--has been described in previous literature, but critical information regarding oviposition behavior and possible differential host parasitism remain cryptic. Here we report on infestation levels of this moth in field populations of paper wasps in Polistes and Mischocyttarus, as well as the oviposition behavior of the moths under a laboratory setting. We found evidence for differential parasitism between paper wasp genera in the field, with almost 50% nest infestation in P. bellicosus and no occurrences of moth infestation in M. mexicanus. Laboratory results revealed that oviposition occurs only at night and is stimulated by contact with the wasp nest or adult wasps. In this setting, eggs were laid largely on the substrate above or adjacent to the host nest, but not on the nest itself. [ABSTRACT FROM AUTHOR]

In basal eusocial wasps the social organization is based on a dominance hierarchy which is maintained through agonistic interactions. The dominant wasp is usually the most aggressive individual and assumes the reproductive function of the colony. These wasps lack morphological caste differences and the physiological conditions and behavioral repertoire define the role of each female in the nest. However, the position in the rank and its function in the colony are not definitive and tradeoffs in the social rank, at least in some species, are common. In this study 8 colonies of Mischocyttarus (M.) montei in pre and post-emergence phases of colonial development were observed in field conditions in order to study the interactions of dominance and subordination among nestmates, thus allowing a better understanding of the establishment of the dominance hierarchy and consequently the social regulation of this species. Our results showed that all colonies in pre-emergence were founded by an association of females which had established the hierarchy previously in their natal nest. Such pattern may contribute to the success of association during pre-emergence, once it tends to reduce conflicts among cohorts during initial phases of colonial development, increasing the chances of colonial success. During post-emergence, the conflicts tend to be more intense, usually involving more physical contacts and in this phase, tradeoffs in the social rank are more frequent. During post-emergence, the number of females increases, more cells are available to lay eggs and the reproductive condition of the main egg-layer is probably reduced, aggravating the competition for reproductive dominance of the colony.

Camouflage is a strategy widely used by various insects in the wild. However, the use of plant material to construct nests is not a widespread habit among the Polistinae. In this study, we describe the nest of Mischocyttarus iheringi Zikán (Hymenoptera: Vespidae) with notes on the use of plant material and the wasps' behavior. [ABSTRACT FROM AUTHOR]

The assassin bug genus Coilopus Elkins, 1969 is recorded for the first time from Colombia. Coilopus vellus Elkins, 1969 is a wasp mimic that was previously recorded from Costa Rica, French Guiana, and Brazil. The Colombian specimens fill the distributional gap between the known Central and South American records. In addition, based on collected wasps from the same place as Coilopus, Mischocyttarus sp. (Vespidae: Polistinae) is proposed as the hymenopteran model of this mimetic harpactorine. [ABSTRACT FROM AUTHOR]

Circadian rhythms in social insects are highly plastic and are modulated by multiple factors. In addition, complex behaviors such as sun-compass orientation and time learning are clearly regulated by the circadian system in these organisms. Despite these unique features of social insect clocks, the mechanisms as well as the functional and evolutionary relevance of these traits remain largely unknown. Here we show a modification of the Drosophila activity monitoring (DAM) system that allowed us to measure locomotor rhythms of the honey bee, Apis mellifera (three variants; gAHB, carnica and caucasica), and two paper wasps (Polistes crinitus and Mischocyttarus phthisicus). A side-by-side comparison of the endogenous period under constant darkness (free-running period) led us to the realization that these social insects exhibit significant deviations from the Earth's 24 h rotational period as well as a large degree of inter-individual variation compared with Drosophila. Experiments at different temperatures, using honey bees as a model, revealed that testing the endogenous rhythm at 35°C, which is the hive's core temperature, results in average periods closer to 24 h compared with 25°C (23.8 h at 35°C versus 22.7 h at 25°C). This finding suggests that the degree of tuning of circadian temperature compensation varies among different organisms. We expect that the commercial availability, cost-effectiveness and integrated nature of this monitoring system will facilitate the growth of the circadian field in these social insects and catalyze our understanding of the mechanisms as well as the functional and evolutionary relevance of circadian rhythms. [ABSTRACT FROM AUTHOR]

The benefits of cooperation are essential in driving group formation. However, an individual can gain significant benefits by acting selfishly at a substantial cost to others in the group. Thus, group members must find a balance between accepting and rejecting potential new members. Here, I explore the factors that mediate acceptance of non-related individuals during the period of group establishment in the primitively eusocial wasp Mischocyttarus mexicanus. In this species, group composition changes during establishment, with non-related females (non-nestmates) sometimes accepted into a foreign colony. By experimentally introducing non-nestmates to newly established colonies, I test the hypothesis that acceptance threshold of nestmates towards non-nestmates shifts depending on the ecological context, as predicted by the Optimal Acceptance Threshold Model. I explored how non-nestmate age (young vs. old), stage of colony establishment (early vs. late), initial behavior of the non-nestmates (non-aggressive vs. aggressive), and the behavioral response by nestmates (non-aggressive vs. aggressive) affected the rates of acceptance. My results show an effect of both non-nestmate age and stage of colony development on non-nestmate acceptance. Young non-nestmates were more frequently accepted in early than in late colonies. Late colonies more frequently rejected both young and old non-nestmates, suggesting a cost of accepting potential usurpers into late colonies. Surprisingly, non-nestmate aggressive behavior did not have a direct effect on their acceptance, but it triggered an aggressive response from nestmates. These findings reveal a shift in the acceptance threshold, suggesting an effect of the social context and the specific needs of a colony on non-nestmate acceptance. [ABSTRACT FROM AUTHOR]

In this study, we recognize and review a total of 19 species of the genus Symmorphus Wesmael from China. We also provide a key to these species. Three new species are described and illustrated, namely Symmorphus (Symmorphus) tianchiensis Li & Chen, sp. n., S. (S.) cavatus Li & Chen, sp. n., and S. (S.) nigriclypeus Li & Chen, sp. n. The following four species are newly recorded from China: Symmorphus (S.) fuscipes (Herrich-Schaeffer), S. (S.) lucens (Kostylev), S. (S.) sublaevis Kostylev, and S. (S.) violaceipennis Giordani Soika. In addition, we map the species geographical distributions in China of these 19 species. Type specimens of these three new species are deposited in Chongqing Normal University and Yunnan Agricultural University. [ABSTRACT FROM AUTHOR]

The insects known as thrips are commonly thought of as flower-living and pestiferous organisms, but we report here a novel interaction between a phlaeothripine thrips species, Mirothrips arbiter gen. et sp. nov. and three species of social paper wasps in Brazil. This thrips species breeds inside the wasp colonies, and larval and adult thrips feed on wasp eggs, which become severely damaged. Infested nests can contain up to 300 M. arbiter gen. et sp. nov. individuals. The closest relatives of M. arbiter are two presumably predaceous species: Mirothrips bicolor sp. nov., which inhabits abandoned Cecidomyiidae galls, and Mirothrips analis comb. nov., described from individuals collected in the silken bags of the caterpillars of Psychidae moths. The behaviour exhibited by M. arbiter represents one of the most evolutionarily advanced lifestyles known among Thysanoptera, and we predict that other polistine species serve as hosts for this thrips in Brazil. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 332-341. [ABSTRACT FROM AUTHOR]

The article discusses a study to determine the existence of social parasitism and dynamics among cuticular hydrocarbons (CH) worker species of Mischocyttarus (M.) consimilis and Mischocyttarus (M.) cerberus. It proposes that social parasites M. consimilis are able to remain in the colony of its host, M. cerberus through the use of chemical signals. The researchers cite the efficacy of Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS) in detecting the CH levels of the worker species. The study demonstrates that female parasites of the M. consimilis species are able to complete parasitic contact by altering the chemical profiles of their host-specie, as well as, their own.

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Mischocyttarus cassununga, a primitively eusocial Brazilian wasp, commonly found in urban environments, is an interesting model for studies on the evolution of social behaviour in hymenopteran insects. In this study, we constructed a microsatellite-enriched genomic library and presented primers for 18 microsatellite loci. For the analysis, 20 unrelated females were screened and all loci obtained were polymorphic. PCR amplification revealed from 3 (Mcas5b) to 17 (Mcas53b) alleles per locus ( $$ \overline{x} = 8.3 $$). We detected the levels of observed ( H) and expected ( H) heterozygosities ranging from 0.150 to 0.950 and 0.261 to 0.920, respectively. The polymorphic information content ranged from 0.238 to 0.915, averaging 0.680. All loci were in Hardy-Weinberg equilibrium and linkage disequilibrium was not detected after sequential Bonferroni correction ( P > 0.05). These molecular markers will allow further studies on sociogenetic structure, extensive population genetic analysis and diversity of M. cassununga and other Mischocyttarini species. [ABSTRACT FROM AUTHOR]

The article discusses a study on invasive species Polistes dominula in Wyoming and western South Dakota and offers data on the early nesting dynamics of said invasive species and that of the native Polistes and Mischocyttarus species in western South Dakota. Polistes and Mischocyttarus nests at 27 sites in the northern Black Hills region and the surrounding prairie of South Dakota were surveyed from July to September of 2011 while records of wasps and wasp nests of both genera were reviewed for a historical view of species distributions. It suggests that P. dominula's population density and activity level may be a factor in the observed decrease in the number of P. fuscatus nests although the behavior of M. flavitaris does not seem to be impacted by the presence of new Polistes species.

The article discusses a study which evaluated the division of labor between castes, and the temporal polyethism in workers of eusocial wasp Mischocyttarus consimilis. Study authors analyzed the behavioral repertory and temporal polyethism of the species. They concluded that using hybrid multidimensional scaling showed a division between queens and workers, which showed the physical dominance and food solicitation characteristics of the queen caste.

In Trinidad, West Indies, wasps matching the description of Mischocyttarus alfkenii build two readily distinguishable nest forms, differing both in architecture (excentric versus centric petiole) and colour (yellowish grey-brown versus reddish medium brown). Analysis of two mitochondrial genes ( 16S and cytochrome c oxidase subunit I, COI) in excentric- and centric-form M. 'alfkenii' consistently segregates individuals from the two nest forms, with genetic divergences comparable with those observed among other species in the genus. Geometric morphometric analysis of wing venation likewise recovers consistent differences between nest forms. Integrating behavioural, genetic and morphometric evidence corroborates the hypothesis that the two nest forms correspond to distinct species of recent common ancestry. Notes accompanying the description of M. alfkenii indicate that the name belongs to the species in which the nest has an excentric petiole and paler carton. The other species is described as Mischocyttarus baconi [ABSTRACT FROM AUTHOR]

Richards (1978) misinterpreted geographic information presented by Ducke (1905) on the collecting localities of type specimens of Megacanthopus undulatus Ducke, 1905. In so doing, Richards treated as a type of this species a male of a very different form, and further included in his “undulatus” concept other specimens of a distinct third species. In the present article this latter taxon is described as Mischocyttarus xavante n. sp. Richards (1978) confundiu informacoes originais sobre as localidades de coleta dos tipos de Megacanthopus undulatus Ducke (1905). Por causa disso, ele tratou como tipo dessa especie um macho de outra completamente diferente, e ainda incluiu no conceito exemplares de uma terceira especie. No presente artigo, este ultimo taxon e descrito como Mischocyttarus xavante sp. n. [ABSTRACT FROM AUTHOR]

The article presents a study on the social factors that regulate the development of colonies of Mischocyttarus cassununga. The researchers focused on the pattern of establishment and manipulation of the social hierarchy by the dominant individuals, which is believed to have an influence on the longevities of queens. They observed five colonies during the post-emergence phase to assess the factors that will determine the pattern of social regulation during the development of colonies of M. cassununga. They found that females spent less time away from the nest and displayed higher rates of dominance behaviors.

In many animal societies, an individual’s opportunities to reproduce correspond to their position in a dominance hierarchy. In primitively eusocial paper wasps, female social dominance and direct reproduction are positively associated with taking food from nest mates, but both negatively correlate with foraging flights. Female paper wasps reproduce by laying eggs in their nest, while males reproduce by leaving the nest to copulate. Males of Mischocyttarus mastigophorus are unusual because they reside on their natal nests for prolonged periods, and males direct aggression towards female nestmates. Mischocyttarus mastigophorus males provide an opportunity to further analyse the relationships between dominance, nutrition and nest departure. We found males’ rates of social aggression, food taking behaviour, and rates of nest departure were positively correlated. Furthermore, males that initiated aggression at younger ages also began flying earlier, and males engaged in all three behaviours at younger ages than females. Male social aggression may lead to nutrient acquisition, which enable males to depart from the nest. We hypothesise that male nest departure could be adaptive if it increases male mating opportunities. This could account for the positive relationship between dominance and nest departure for males. [ABSTRACT FROM AUTHOR]

The primitive eusocial wasp Mischocyttarus cerberus forms colonies of independent foundation, without morphological differentiation among castes. Ants are natural enemies of the social wasps and defending the wasps’ nests involves chemical and active defense strategies. The aims of this work were to verify the kind of defense the wasps use most frequently in post-emergent colonies of M. cerberus. We also observed whether the nest was abandoned during the ant attack and whether any relationship existed between the forms that colony defense took and the number of adults, the number of cells, and the number of immature wasps. The study was carried out on the campus of Universidade Estadual Paulista of Rio Claro, São Paulo, Brazil. The 23 nests under study were mapped weekly, and 68 bioassays were performed by simulating ant attacks against the nests. The results showed that wasps used both active and chemical strategies for nest defense, and the PCA analysis showed that the aggressive behaviors of biting the ant, wings vibrating, gaster hitting, and abdomen pumping were the dominant terms; the PCA correlation values were 2.70, 2.54, 1.64, and 1.63, respectively. The colonies in pre- and post-male substages with few immature wasps and the nests in post-male substage with one adult were more correlated with the nonaggressive behaviors of hiding, staying immobile, and flying; their PCA correlation values were 3.12, 2.56, and 1.77, respectively. These results show that the number of immature wasps is an important factor in the kind and in the intensity of the defense behavior against ant attacks. [ABSTRACT FROM AUTHOR]

The expression of alternative traits that benefit eusocial individuals but are not directly involved in reproductive differences among those individuals, which I call ‘eusocially selected traits’, may vary in response to environmental changes if this increases an individual's inclusive fitness. In this study, I describe traits that separate individuals within the reproductive division of labor of Mischocyttarus mexicanus, a eusocial paper wasp, and determine whether observed eusocially selected traits vary across seasons. I examined M. mexicanus because females initiate new nests throughout most of the year where they experience different conditions depending on the season. Findings from this study suggest two main conclusions: (1) phenotypic differences among M. mexicanus females are mixed, showing specialized, generalized, and context-dependent eusocially selected traits and (2) a female's position within the reproductive division of labor may be influenced by its state. The presence of context-dependent traits, e.g. large females initiated solitary nests in the spring and grouped nests during the summer, suggests that the payoff for pursuing different positions within the reproductive division of labor changes across seasons. The expression of context-dependent eusocially selected traits also suggests that, roles, instead of castes, may better reflect the reproductive division of labor among individuals of eusocial species like M. mexicanus. [ABSTRACT FROM AUTHOR]