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When helpers from cooperative breeding animals have some expectation of direct reproduction, there is potential for conflict over how much aid they should provide to the colony. For example, if food is shared among all colony members, then higher levels of foraging by a helper would be desirable for the colony as a whole. However, because foraging is risky and physiologically costly, hopeful reproductive helpers could avoid foraging. Evidence suggests that this work-conflict could be resolved if helpers are aggressively coerced by their nestmates to provide aid. Here, we showed that in the primitively eusocial paper wasp Polistes versicolor, colony food starvation leads to an increasing in aggression that results in an increasing activity level (including foraging). We propose that aggression affects forage levels because (i) attacks from nestmates are directed toward known foragers rather than non-foragers; and (ii) resting wasps generally respond to aggression by becoming more active while already active wasps generally respond by switching the task they were doing. In P. versicolor, direct reproduction is an option for helpers. It means that they can be considered as hopeful reproductive individuals seeking to avoid performing risky behaviours, like foraging. In this sense, decentralized aggression from nestmates could be a coercive mechanism to force wasps performing undesirable tasks, while simultaneously enhancing the performance of a variety of other tasks. [ABSTRACT FROM AUTHOR]

The founding individuals of a new group or lineage are uniquely poised to have long-lasting effects on their descendants. Here we explore how the behavioural traits of new foundresses influence their task allocation strategies and the downstream collective behaviour of their colonies. We collected individual paper wasp ( Polistes metricus ) queens from the wild and measured their boldness, aggressiveness, exploration, activity and time budgets in the laboratory. We then provided queens with food and nest materials and waited for their workers to eclose. We subsequently tested for links between queen behavioural traits (e.g. boldness, aggressiveness) and the collective aggressiveness of their colonies, as estimated by the number of workers that responded to and stung a model predator. We found that bolder queens (i.e. queens that were less likely to leave their nests after repeated exposure to an agonistic stimulus) spent more time nest guarding, reared more workers and produced groups that were less responsive to a model predator. Thus, there appears to be parent–offspring, or queen–worker, resemblance in the degree to which individuals remain on their nests in different social contexts (solitary queen versus queen + her worker group). To our knowledge this represents the first study to explicitly test for links between individual variation in foundress behaviour, worker production and intercolony collective behaviour; the results highlight the possibility that cross-contextual and transgenerational behavioural links could be a reasonably common and potentially important phenomenon in complex societies. [ABSTRACT FROM AUTHOR]

In cooperatively breeding vertebrates, the existence of individuals that help to raise the offspring of non-relatives iswell established, but unrelated helpers are less well known in the social insects. Eusocial insect groups overwhelmingly consist of close relatives, so populations where unrelated helpers are common are intriguing. Here, we focus on Polistes dominula--the best-studied primitively eusocialwasp, and a species in which nesting with non-relatives is not only present but frequent.We address two major questions: why individuals should choose to nest with non-relatives, and why such individuals participate in the costly rearing of unrelated offspring. Polistes dominula foundresses produce more offspring of their own as subordinates than when they nest independently, providing a potential explanation for co-founding by non-relatives. There is some evidence that unrelated subordinates tailor their behaviour towards direct fitness, while the role of recognition errors in generating unrelated co-foundresses is less clear. Remarkably, the remote but potentially highly rewarding chance of inheriting the dominant position appears to strongly influence behaviour, suggesting that primitively eusocial insects may have much more in common with their social vertebrate counterparts than has commonly been thought. [ABSTRACT FROM AUTHOR]

Many animals have ornaments that mediate choice and competition in social and sexual contexts. Individuals with elaborate sexual ornaments typically have higher fitness than those with less elaborate ornaments, but less is known about whether socially selected ornaments are associated with fitness. Here, we test the relationship between fitness and facial patterns that are a socially selected signal of fighting ability in Polistes dominula wasps. We found wasps that signal higher fighting ability have larger nests, are more likely to survive harsh winters, and obtain higher dominance rank than wasps that signal lower fighting ability. In comparison, body weight was not associated with fitness. Larger wasps were dominant over smaller wasps, but showed no difference in nest size or survival. Overall, the positive relationship between wasp facial patterns and fitness indicates that receivers can obtain diverse information about a signaler's phenotypic quality by paying attention to socially selected ornaments. Therefore, there are surprisingly strong parallels between the information conveyed by socially and sexually selected signals. Similar fitness relationships in social and sexually selected signals may be one reason it can be difficult to distinguish the role of social versus sexual selection in ornament evolution. [ABSTRACT FROM AUTHOR]

Sexually selected signals are theoretically expected to exhibit heightened condition dependence compared to non-signaling traits. This link to condition enables sexual signals to provide information regarding individual quality and also provides a mechanism that allows animals to develop signals that accurately reflect their abilities. Most previous work on sexual signal condition dependence has focused on signals that have clear developmental costs, while less is known about the development of other types of quality signals. Male Polistes dominulus paper wasps have yellow-on-black abdominal spots that are important signals during female choice and male-male competition. These signals lack obvious production costs, as males are covered in yellow and black patterns composed of the same pigments. Here, we assess signal condition dependence by testing whether larval diet has a stronger influence on the development of male spots than on the development of control traits composed of the same pigments. Males reared on ad libitum diets developed elliptical spots similar to those seen on dominant, attractive males, while males reared on restricted diets developed irregularly shaped spots similar to those seen on subordinate, unattractive males. Remarkably, the development of a control trait composed of the same yellow and black pigments was not influenced by larval diet. Therefore, sexually selected signals can be developmentally decoupled from traits comprised of the same pigments. Condition dependence of sexually selected signals is likely to be a widespread solution to the challenge of developing sexually selected signals that accurately convey information about individual quality. [ABSTRACT FROM AUTHOR]

Animals frequently face situations where they must choose one prey item from a set of options. Animals are often considered to be able to choose the best prey item from multiple alternatives. However, time may be required to make accurate decisions, and under natural conditions, time is usually limited. Here, we examined whether animals fail to choose the most profitable prey item under time-limited conditions. A queen (foundress) of a paper wasp Polistes chinensis antennalis starts a colony in spring and maintains the nest alone until the emergence of workers. At the stage, the foundress often depredates larvae in other conspecific nests. The intruder needs to finish choosing and extracting a single larva during the absence of the owner from the nest. Intruders preferred the fifth-instar larvae, which are the largest and the most profitable prey among larvae. When the time spent in choosing was long, intruders were able to choose the fifth-instar larvae with a higher probability. However, when the time spent in choosing was short, intruders sampled only a small fraction of larvae in a nest, and the probability of choosing the fifth-instar larvae decreased. Furthermore, we found that intruders decreased the time spent in choosing under higher time constraints. These results suggest that under time-limited conditions, intruders occasionally failed to choose the most profitable prey item because of incomplete information on the availability of options. These results also suggest a trade-off between speed and accuracy of choosing the best item from a set of options. [ABSTRACT FROM AUTHOR]

We simulated intraspecific usurpation in two species of paper wasps at a field site in Michigan to compare the species' treatment of foreign brood. Queens of Polistes fuscatus, a species that commonly uses intraspecific usurpation as an alternative reproductive tactic, destroyed significantly fewer large larvae and significantly more small larvae than queens of P. dominulus, a sympatric species that rarely usurps. The pattern of brood destruction exhibited by P. fuscatus was consistent with the previously published findings that P. fuscatus usurpers destroy reproductive-destined brood (eggs and small larvae), but not worker-destined brood (large larvae and pupae) that are subsequently used by a usurper to raise her own reproductives. The pattern of brood destruction displayed by P. dominulus differed from that of Polistes species that frequently engage in intraspecific usurpation. The brood destruction pattern in P. dominulus may have been shaped by nest adoption, a common alternative reproductive tactic in this species. If so, it is not clear why P. dominulus would destroy large, worker-destined larvae. [ABSTRACT FROM AUTHOR]

Theory on animal contests often assumes that individuals can rapidly and accurately assess their own resource-holding potential (RHP). In empirical work, individuals behave as if they ‘know’ their own RHP, but little is known about how such assessment occurs. Here, we test how juvenile hormone (JH) influences precontest behaviour in P. dominulus paper wasps. Previous work has shown that P. dominulus have variable black facial patterns that are a signal of agonistic ability and that JH influences fighting ability. In this experiment, we tested how JH influences rival challenge behaviour in the absence of direct social competition. Wasps were given the opportunity to challenge or avoid a model wasp guarding a patch of food. Individuals treated with the JH analogue methoprene were more likely to challenge rivals than were control individuals, and they also had a shorter latency to challenge than controls. However, hormone treatment was only one of multiple factors that influenced behaviour, suggesting that assessment prior to contests is based on the interplay between individual physiology and social context. Contest decisions were also dependent on a wasp's own facial pattern and mass, as well as the facial pattern of its rival. Interestingly, these complex assessment decisions occurred in the absence of direct social cues that could be acquired during a contest. These results are consistent with JH playing a role in self-assessment of RHP. Hormones such as JH are influenced by the physical and social environment, so they provide diverse information about relative RHP and may be commonly involved in assessment behaviour. [ABSTRACT FROM AUTHOR]

Status signals function in a number of species to communicate competitive ability to conspecific rivals during competition for resources. In the paper wasp Polistes dominulus, variable black clypeal patterns are thought to be important in mediating competition among females. Results of previous behavioral experiments in the lab indicate that P. dominulus clypeal patterns provide information about an individual’s competitive ability to rivals during agonistic interactions. To date, however, there has been no detailed examination of the adaptive value of clypeal patterns in the wild. To address this, we looked for correlations between clypeal patterning and various fitness measures, including reproductive success, hierarchical rank, and survival, in a large, free-living population of P. dominulus in southern Spain. Reproductive success over the nesting season was not correlated with clypeal patterning. Furthermore, there was no relationship between a female’s clypeal patterning and the rank she achieved within the hierarchy or her survival during nest founding. Overall, we found no evidence that P. dominulus clypeal patterns are related to competitive ability or other aspects of quality in our population. This result is consistent with geographical variation in the adaptive value of clypeal patterns between P. dominulus populations; however, data on the relationship between patterning and fitness from other populations are required to test this hypothesis. [ABSTRACT FROM AUTHOR]

Background The study objectives were: (1) to field test potential repellency of common essential oils against several pestiferous social wasps (Hymenoptera: Vespidae), using attractant-baited traps; (2) to identify vespid antennally active compounds from the repellent essential oils; (3) to determine potential repellency of these electroantennographic detection ( EAD) active compounds in the field. Results Of the 21 essential oils tested, 17 showed significant repellency on yellowjackets [mainly Vespula pensylvanica (Saussure)] and paper wasps [mainly Polistes dominulus (Christ)]: clove, pennyroyal, lemongrass, ylang ylang, spearmint, wintergreen, sage, rosemary, lavender, geranium, patchouli, citronella, Roman chamomile, thyme, fennel seed, anise and peppermint. Two essential oil mixtures - 3EO-mix (clove, geranium and lemongrass) and 4EO-mix (clove, geranium, lemongrass and rosemary) - totally blocked the attraction of vespid workers. Twenty-nine vespid antennally active compounds were identified from solid-phase microextraction ( SPME) samples of 11 strongly repellent essential oils by GC-EAD/ MS techniques. Among the synthetic EAD-active compounds field tested, eugenol, P/ I-menthone, pulegone, α/ β-thujone, l-carvone, E/ Z-citral, citronellal, methyl benzoate, benzyl acetate, methyl salicylate and 3-octanol showed a significant repellency on vespid workers. These compounds are likely responsible for the repellency of their corresponding essential oils. Conclusion These repellent essential oils and their active compositions have great potential for efficient, environmentally sound semiochemical-based IPM of pestiferous vespid wasps. © 2012 Society of Chemical Industry [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.

Some animals minimize the high costs of aggressive conflict by using conventional signals of agonistic ability to assess rivals prior to interacting. Conventional signals are more controversial than other signals of agonistic ability because they lack an inherent physical or physiological link with their bearer's agonistic ability. Here, we test whether the variable brown facial stripes in Polistes exclamans paper wasps function as a conventional signal. Polistes exclamans were given the option of challenging or avoiding a rival with an experimentally altered facial pattern. Our results show that rival assessment is based on the facial patterns of rivals, as well as an individual's own size, facial patterns, and nesting strategy. Individuals with larger body size and larger brown facial stripes were more likely to challenge rivals than individuals with smaller body size and smaller brown facial stripes. In addition, large individuals were more likely to challenge rivals with large brown facial stripes than small individuals, while an individual's own body size did not influence whether or not they challenged rivals with small brown stripes. Individuals who previously nested in multiple queen groups approached rivals more rapidly than individuals who previously nested alone, suggesting that social experience also plays a role in rival assessment. Finally, rivals with small facial stripes were challenged more rapidly than those with large facial stripes. These results demonstrate that P. exclamans facial patterns function as a signal used to minimize the cost of conflict. However, individuals do not make simple decisions based on their rival's signal alone, as an individual's own social experience and agonistic abilities also influence rival assessment decisions. [ABSTRACT FROM AUTHOR]

Insect social parasites need to overcome host colonies’ defences to exploit their resources successfully. Sophisticated sensory deception mechanisms to break the host’s barriers have been repeatedly reported for many social parasites, possibly concealing the importance of open fighting, a more ancestral strategy. Understanding the relative importance of fooling and fighting is primarily challenging when the two strategies seem both available and advantageous. We focused on the paper wasp social parasite–host system Polistes sulcifer–P. dominulus, where both fooling and fighting have been suggested to play a role during usurpation contests. Host aggression is elicited by the chemical cues (hydrocarbons) that intruders bear on their cuticle. Parasites would benefit from reducing the amount of these cues before approaching the host colony. In addition, the parasites’ facial pattern has been shown to reduce the host’s aggressive reaction, probably by amplifying the mandibular width. We tested the occurrence of chemical and visual cheating through chemical analyses and laboratory usurpation trials, respectively. Usurping parasites did not conceal their identity by reducing cuticular hydrocarbons, nor did their facial pattern facilitate nest take-over. Contest outcome was instead predicted by the relative body size of the opponents. Fighting, rather than fooling, is therefore the strategy used by P. sulcifer usurping females. The importance of physical strength could thus explain why chemical or visual tricks do not play a role in taking over the host colony despite their potential usefulness. Our findings suggest that the evolution of sophisticated cheating mechanisms can be prevented by the ability to fight. [Copyright &y& Elsevier]

Contests between individuals over resources may be costly in terms of both time and energy expended and the risk of injury. Signals of status, or ‘status badges’, are thought to have evolved to minimize these costs by providing information about an individual’s fighting ability or resource-holding potential (RHP) at the start of a contest. Studies on recently established North American populations of the paper wasp Polistes dominulus have demonstrated the existence of a status badge, in the form of black clypeal patterns, and have shown that rivals attend to these patterns during competitive interactions. However, observational data from studies in this wasp’s native European range have failed to demonstrate a strong link between clypeal patterning and RHP. We undertook the first direct test of status signalling in a European population of P. dominulus, by testing receiver responses to clypeal pattern manipulations in a competitive foraging context. We found no evidence that individuals assessed rivals using the clypeal ‘badge’. We discuss possible reasons for variation in signal use between the American and European populations, including genetic drift and environmental effects of the development and transmission of the signal. [Copyright &y& Elsevier]

The paper wasp Polistes dominulus is unique among the social insects in that nearly one-third of co-foundresses are completely unrelated to the dominant individual whose offspring they help to rear and yet reproductive skew is high. These unrelated subordinates stand to gain direct fitness through nest inheritance, raising the question of whether their behaviour is adaptively tailored towards maximizing inheritance prospects. Unusually, in this species, a wealth of theory and empirical data allows us to predict how unrelated subordinates should behave. Based on these predictions, here we compare helping in subordinates that are unrelated or related to the dominant wasp across an extensive range of field-based behavioural contexts. We find no differences in foraging effort, defense behaviour, aggression or inheritance rank between unrelated helpers and their related counterparts. Our study provides no evidence, across a number of behavioural scenarios, that the behaviour of unrelated subordinates is adaptively modified to promote direct fitness interests. [ABSTRACT FROM AUTHOR]

In order to understand how the apparent freedom of individual movements can concur with social order in a colony, we investigated spatial relationships between foundresses, workers and immature brood in a paper wasp. This is the first time an ecological analytical approach (home range analysis) has been employed to describe small scale spatial use in a social context. In this study, home range was not used in its strictly ecological sense, but rather applied to the comb. Our results show that the positions individual wasps assumed on Polistes dominulus combs are spatially structured. Workers and foundresses do not occupy the comb in random distribution, but rather follow predictable spatial patterns. Each active wasp has its own spatial fidelity area, at least over a 1 d observation period, spending the majority of its time within a very small area averaging approx. 12% of the comb but occasionally it may cover an area of up to 50% of the comb surface. Dominant females occupied a significantly smaller area that either subordinate foundresses or workers. Areas patrolled by workers varied in shape and size, with no relation to time spent on the comb, wasp density or position of immature brood. All the wasps clumped around the dominant female, who proved to be the only individual affected by cell content. Nevertheless, although the wasps tended to clump together, average superimposition rates among nest-mates was very low (higher in workers than foundresses), suggesting that the wasps limit each other’s individual spaces. [ABSTRACT FROM AUTHOR]

In primitively eusocial societies, all individuals can potentially reproduce independently. The key fact that we focus on in this paper is that individuals in such societies instead often queue to inherit breeding positions. Queuing leads to systematic differences in expected future fitness. We first discuss the implications this has for variation in behaviour. For example, because helpers nearer to the front of the queue have more to lose, they should work less hard to rear the dominant's offspring. However, higher rankers may be more aggressive than low rankers, even if they risk injury in the process, if aggression functions to maintain or enhance queue position. Second, we discuss how queuing rules may be enforced through hidden threats that rarely have to be carried out. In fishes, rule breakers face the threat of eviction from the group. In contrast, subordinate paper wasps are not injured or evicted during escalated challenges against the dominant, perhaps because they are more valuable to the dominant. We discuss evidence that paper-wasp dominants avoid escalated conflicts by ceding reproduction to subordinates. Queuing rules appear usually to be enforced by individuals adjacent in the queue rather than by dominants. Further manipulative studies are required to reveal mechanisms underlying queue stability and to elucidate what determines queue position in the first place. [ABSTRACT FROM AUTHOR]

Abstract: Adult workers of some social insect species show dramatic behavioral changes as they pass through a sequence of task specializations. In the paper wasp, Polybia aequatorialis, female workers begin adult life within the nest tending brood, progress to maintaining and defending the nest exterior, and ultimately leave the nest to forage. The mushroom body (MB) calyx neuropil increases in volume as workers progress from in-nest to foraging tasks. In other social Hymenoptera (bees and ants), MB Kenyon cell dendrites, axons and synapses change with the transition to foraging, but these neuronal effects had not been studied in wasps. Furthermore, the on-nest worker of Polybia wasps, an intermediate task specialization not identified in bees or ants, provides the opportunity to study pre-foraging worker class transitions. We asked whether Kenyon cell dendritic arborization varies with the task specialization of Polybia workers observed in the field near Monteverde, Costa Rica. Golgi-impregnated arbors in the lip and collar calyces, which receive a predominance of olfactory and visual input, respectively, were quantified using Sholl’s concentric circles and a novel application of virtual spherical probes. Arbors of the lip varied in a manner reminiscent of honeybees, with foragers having the largest and in-nest workers having the smallest arbors. In contrast, arbors of the collar were largest in foragers but smallest in on-nest workers. Thus, progression through task specializations in P. aequatorialis involves subregion specific dendritic growth and regression in the MB neuropil. These results may reflect the sensitivity of Kenyon cell dendritic structure to specialization dependent social and sensory experience. [Copyright &y& Elsevier]

Most research on animal contests has focused on the factors that influence the intensity and outcome of aggressive contests within nonsocial species, while relatively little is known about contests in social taxa. Here, we examine contests among queens of the social paper wasp, Polistes dominulus. Queens use multiple reproductive strategies, including nesting alone, usurping established colonies, and cooperatively joining other queens. We stage contests between a nesting queen and a challenger to test how resource value (RV) and resource holding potential (RHP) influence (a) who occupies the nest at the end of the contest and (b) the extent of conflict between the queen and challenger. We found that RHP, as measured by individuals’ facial patterns and body size, influenced the outcome of the contest. Challengers with high RHP were more likely to successfully usurp the nest than challengers with low RHP. Interestingly, queens with relatively high RHP were more likely to form a cooperative association with the challenger than queens with lower RHP, suggesting that queens may evict individuals that are an aggressive threat. RV influenced the intensity of conflict. There was more aggressive conflict over large nests than over small nests. Overall, social taxa have complex contest dynamics with important parallels to contests in nonsocial taxa. Studying contests in social taxa provides an important perspective on the factors that influence individual decisions about conflict versus cooperation. [ABSTRACT FROM AUTHOR]

In animals, restlessness is a strategy to fulfil a goal within a narrow seasonal window when ecological and physiological constraints require the performance of certain fundamental events. Although restlessness can be expected in parasitic species that have their biological cycle similar to that of the host, no ‘urge to parasitize’ has thus far been demonstrated in any host-parasite pair. The paper wasp, Polistes sulcifer, is a social parasite that has lost the nest-building ability and marked by the absence of the worker caste; it depends on a congeneric host species to reproduce. Host colony usurpation is successful when it occurs in a well-defined seasonal window. The short time available for host-nest usurpation might lead to parasite restlessness that overlaps this period. Under controlled laboratory conditions, we demonstrated that the parasite females exhibit ‘usurpation restlessness’ during the period in which field usurpations occur. Additional experiments showed that both this period and laboratory temperature influence the parasite’s ‘urge to usurp’. [ABSTRACT FROM AUTHOR]

Abstract  In temperate climates, female paper wasps typically initiate new colonies in the spring. Several nest-founding tactics have been documented in Polistes species, including solitary nest initiation, joining a cooperative association, usurping an existing nest, or adopting an abandoned nest. Occasionally, exceptionally large groups of females have also been found reusing nests from the previous season. Here we report this phenomenon in introduced populations of the Eurasian species Polistes dominulus. We describe in detail the demographic and genetic characteristics of one such spring colony from Los Angeles, California, USA, which was collected with 84 associated adults and all stages of developing brood in its 613 cells. Genetic and morphological data indicate the presence of multiple reproductively active females of varying relatedness, as well as many nonbreeding females, including probable early-produced offspring. Despite some evidence of chaotic social conditions, the colony appeared to have been highly productive. Additional observations of similar colonies are needed to determine how control is maintained within such a large breeding aggregation. [ABSTRACT FROM AUTHOR]

Unique among insects, some paper wasp species recognize conspecific facial patterns during social communication. To evaluate whether specialized brain structures are involved in this task, we measured brain and brain component size in four different paper wasp species, two of which show facial pattern recognition. These behavioral abilities were not reflected by an increase in brain size or an increase in the size of the primary visual centers (medulla, lobula). Instead, wasps showing face recognition abilities had smaller olfactory centers (antennal lobes). Although no single brain compartment explains the wasps’ specialized visual abilities, multi-factorial analysis of the different brain components, particularly the antennal lobe and the mushroom body sub-compartments, clearly separates those species that show facial pattern recognition from those that do not. Thus, there appears to be some neural specialization for visual communication in Polistes. However, the apparent lack of optic lobe specialization suggests that the visual processing capabilities of paper wasps might be preadapted for pattern discrimination and the ability to discriminate facial markings could require relatively small changes in their neuronal substrate. Copyright © 2007 S. Karger AG, Basel [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]

The abdominal wagging behavior of Polistes dominulus foundresses is highly conspicuous and frequently performed, but comprehensive descriptions are lacking. It has been suggested that abdominal wagging is involved in vibratory signaling, but the wagging behavior has not been distinguished from the substrate-borne signal, and nest vibrations have never been described. Here I provide a detailed description of the behavior and the first video-linked accelerometer recordings of nest vibrations. These recordings indicate that an impulsive vibration is produced when the adult female repeatedly strikes its abdomen against cell rims as it swings it across the nest surface. These strong vibrations propagate throughout the nest. Scanning electron microscopy reveals no specialized structures for vibration production on the abdomen or nest. These results provide a foundation for the mechanical playback studies required to experimentally determine the function of abdominal wagging. [ABSTRACT FROM AUTHOR]

The mushroom bodies (MB) are a complex neuropil in insect brains that have been implicated in higher-order information processing such as sensory integration and various types of learning and memory. Eusocial insects are excellent models to test functional neural plasticity in the MB because genetically related nest mates differ in task performance, environmental experience and social interactions. Previous research on eusocial insects shows that experience-dependent changes in brain anatomy (i.e., enlarged MB calyces) are positively correlated with task performance and social interactions. In this study, we quantified relationships of task performance and social and reproductive dominance with MB volume in Polistes instabilis, a primitively eusocial paper wasp. We used experimental removals of dominant workers to induce changes in aggressive behavior and foraging by workers. Ovary development and social dominance were positively associated with the volume of the MB calyces relative to the region containing the Kenyon cell bodies. In contrast to highly eusocial insect workers, foraging behavior was not positively correlated with MB calycal volume. We conclude that mushroom body volume is more strongly associated with dominance rank than with foraging behavior in Polistes instabilis. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The idea that insects play has often aroused skepticism. Nevertheless, the authors investigated the occurrence of a playlike behavior in young individuals of a paper wasp. Polistes dominulus foundresses hibernate in aggregations and found associative nests in the spring. In aggregations, wasps exhibit most of the rank-dependent behaviors that they will use in the nest 6 months later. In aggregations, precocious dominance interactions are performed with exaggerated frequencies, whereas aggression and trophallaxis are rare. Dominance behavior in aggregations is apparently useless, but it probably allows wasps to assess their dominance potential without any apparent reproductive competition. Surprisingly, these interactions may be best interpreted as play because dominance behavior in aggregations shares several features with mammalian play fighting. [ABSTRACT FROM AUTHOR]

Grooming is a commonly observed behavior in many animals. One function of grooming is to clean the body of debris and parasites. An additional function may be to homogenize chemical cues present on the body. This latter purpose is especially likely in species in which contact-based chemical communication occurs, such as in eusocial insects. In this study we address the context, sequence, frequency and duration of 683 acts of self-grooming performed by the paper wasp,Polistes dominulus. In general, individuals groomed heads after cell inspections, and abdomens after sitting, suggesting that grooming serves to remove debris from the body. Although no differences were observed in the total amount of time spent grooming, foundresses groomed significantly more often than did workers. Wasps were equally likely to groom thoraces or abdomens following heads, but were more likely to groom abdomens after thoraces and heads after abdomens. Interestingly, the appendages used to groom individual body parts were highly specific (e.g. the prothoracic legs were used for the head), thus indicating that grooming is not used to homogenize chemical cues across the body surface of the wasp. [ABSTRACT FROM AUTHOR]

Studies the evolution of swarm communication in eusocial paper wasps. Examination of the patterns of correlated evolution between the mode of colony foundation and the presence of sternal exocrine glands; Review of data on worker actions during swarming to determine whether swarm communication behavior was dependent upon gland possession; Achievement of transitions from independent to swarm founding.

Investigates the factors influencing the decision of workers of the paper wasp, Polistes chinensis antennalis, to stay in their natal nest. Factors responsible for the evolution of altruistic behavior; Features of the life insurance advantage hypothesis; Numbers of colonies and half-nests maintained by workers after division of the nest.

Examines the behavior of paper wasp, Polistes fuscatus, when faced with a vertebrate attack over the colony cycle in Rochester, Michigan. Division of labor in the defense against vertebrate predators within a colony; Correlation between the degree of aggression with age of subordinate foundress and workers; Lack of participation of gynes and males in colony defense.

Determines in an experiment whether assessment of relative resource holding potential by conspecific competitors influences the outcome of territory disputes among males of a territorial paper wasp. Possibility of correlation of the size of an opponent with his fighting ability; Withdrawal during compromising aggressive situation as mechanism for the large-size advantage of males.

The paper wasp Polistes exclamans loses part of its brood to the parasitoids Chalcoela iphitalis (Lepidoptera:Pyralidae) and Elasmus polistis (Hymenoptera:Chalcidoidea:Eulophidae) and loses entire nests to bird predation, Crematogaster laeviuscula (Hymenoptera:Formicidae) predation, and orphanage (loss of all adult wasps). More nests fail because of bird predation than from all other causes combined. Larger nests are neither better protected nor more vulnerable to nest predators, though larger nests are less likely to fail because of orphanage than are smaller nests. Larger nests are more heavily attacked by Elasmus polistis, which reinfests its natal nest. Polistes exclamans may subdivide larger groups of females by forming satellite nests because of the lack of an overall advantage to large nests. Satellite nests increase the probability that the brood in either the original nest or satellite nest will avoid bird predation. [ABSTRACT FROM AUTHOR]

Analyzes kin recognition in paper wasps. Assessment of tolerance between aunts and nieces; Description of experimental setup; Recording of interactions between returning and resident wasps; Initiation of interaction by resident females; Comparison of treatment of aunts and nieces with residents and non-residents.

In the laboratory, gynes (potential queens) of the paper wasp, Polistes fuscatus, exposed to both their natal nest and female nestmates (presumably their sisters) discriminate between female nestmates and unrelated females. However, gynes not exposed to their natal nest or conspecifics and gynes exposed only to female nestmates do not discriminate between female nestmates and unrelated females. Thus, the presence of the nest appears to be a requisite for the development of nestmate discrimination. [ABSTRACT FROM AUTHOR]

A correction to the article "Socially selected ornaments and fitness: Signals of fighting ability in paper wasps are positively associated with survival, reproductive success, and rank" which was published in the Volume 69, Number 11 issue is presented.

Low-level social aggression is a conspicuous feature of cooperative animal societies, but its precise function is usually unclear. One long-standing hypothesis is that aggressive displays by dominant individuals serve to reduce uncertainty about relative strength and deter subordinates from starting fights that they are unlikely to win. However, most formal theoretical models of this idea do not consider how the credibility of deterrent signals might change over time in social groups. We developed a simple model of dominant aggression as a deterrent signal, which takes into account how credibility changes over time and how selection should act on receiver memory. We then carried out an experimental test of the predictions of our model on a field population of the paper wasp, Polistes dominulus. The match between our theoretical and empirical results suggests that low-level social aggression can help to maintain the stability and productivity of cooperative associations in this species. Moreover, our work suggests that rates of aggression in animal societies and the robustness of social memories are likely to be intimately related.Social animals often spend a great deal of time and energy being aggressive to one another, for reasons that are not clear. Our experiment on paper wasps shows that aggression can in fact promote peace and harmony in cooperative groups. [ABSTRACT FROM PUBLISHER]

Summary: Remembering individual identity is necessary for the complex, individually-differentiated social relationships found in many vertebrates, including humans. Despite the complexity of social insect colonies, individual social insects are generally thought to have simple, undifferentiated relationships. Here we show that Polistes fuscatus paper wasps, which individually recognize conspecifics, remember the identity of social partners for at least a week, even if they interact with ten other wasps. Therefore, social interactions among paper wasps are based on robust memories of past interactions with particular individuals rather than simple rules. Considering the small size of wasp brains, these results suggest that at least some aspects of social cognition may not be as cognitively demanding as is generally assumed. [Copyright &y& Elsevier]

Presents a thermogram of a hornet being engulfed and baked to death by a ball of bees. Hornets as predators of bees; Defense of bees against hornets.

Discusses research which observed the practice of stuffing male wasps into empty nest cells in a colony of paper wasps. Male wasps forced to remain in cells; Research by Starks and Poe in October 2, 1997 edition of `Nature'; Details about male stuffing; Composition of wasp colonies; Roles of particular wasps; Purpose of stuffing.