Relatedness and altruism in Polistes wasps

Genetic relatedness is expected to play a crucial role in theevolution of altruistic behaviors such as worker behavior inthe social insects. If individuals sacrifice their own reproduction,then the genes for this sacrifice will be lost unless theseindividuals aid the reproduction of others who share the genes.This leads to the prediction that altruism should be most commonin species with high relatedness among potential beneficiaries.Here we report an attempt to test for such an association. Weestimated both the incidence of altruism and the relatednessto potential beneficiaries in foundresses of seven species ofpaper wasps. The predicted positive correlation was not found,and we conclude that factors other than relatedness are moreimportant in determining interspecific differences in the incidenceof altruism.     

Signal response is context-dependent in Polistes dominula

Journal of Ethology - Theory suggests honest status signals mediate agonistic interactions between unfamiliar individuals, but may be less important during interactions between familiar...     

Die Arbeitsteilung der Feldwespe Polistes dubia K.

Ohne Zusammenfassung     

Simulated Intraspecific Usurpations in Paper Wasps: Different Reproductive Tactics Affect Foreign Brood Destruction in Polistes fuscatus and Polistes dominulus

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.     

Queen Succession in the Social Wasp,Polistes annularis

Outcomes of conflicts among social animals can strongly affect individual fitness and therefore partly determine how sociality evolves. In the social wasp, Polistes annularis, conflicts over egg laying result in a linear dominance hierarchy discernible from which wasps attack which others. We investigated the structure and maintenance of dominance hierarchies in colonies containing both nest foundresses and workers. We also investigated the outcome of a potential conflict between foundresses and workers over the identity of the female which becomes queen after the original queen disappears. To investigate queen replacement we recorded individuals' behavior before and after removal of the queen from 13 nests. This experiment simulated natural queen disappearance which occurs frequently. All foundresses were ranked over workers; high ranking females were most aggressive and directed most of their attacks to the female directly beneath them in the hierarchy. This hierarchy determined succession to queenship; the beta female became queen within 3 h. Therefore a foundress became the new queen whenever one was present. There was no evidence of conflict between workers and foundresses when a foundress became queen. This chance of becoming queen contributes to the expected fitness of a female that accepts a subordinate role in spring.     

Grooming Patterns in the Primitively Eusocial Wasp Polistes dominulus

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.     

Wolbachia in the invasive European paper wasp Polistes dominulus

The European paper wasp Polistes dominulus has been expanding its North American range since its introduction in the 1970s. We screened P. dominulus from Italy and the northeastern U.S. for the presence of the intracellular reproductive symbiont Wolbachia. Infection rates among females varied from 16% to 87% among U.S. sites and from 33% to 71% in Italy. We also found infected haploid and diploid males, indicating that this is not a male-killing Wolbachia infection. Our data show that infected individuals from New York, Massachusetts, and Italy carry the same Wolbachia strain, and that some mtDNA haplotypes include both infected and uninfected individuals. We discuss possible implications of Wolbachia infection in this invasive social hymenopteran. Received 28 October 2005; revised 25 January 2006; accepted 17 February 2006.     

The comparative biology of two sympatric paper wasps, the native Polistes fuscatus and the invasive Polistes dominulus (Hymenoptera, Vespidae)

Summary: Polistes dominulus (Christ), an old world paper wasp, was introduced accidentally into the eastern coast of the United States in the late 1970s and has been rapidly spreading westward, displacing the native P. fuscatus (F.). The biology of naturally nesting P. fuscatus and P. dominulus was compared at a field site in Rochester, Michigan. The basic methodology consisted of simultaneously videotaping spatially proximate, matched single-foundress colonies of P. fuscatus and P. dominulus (13 matched sets, 176.8 h of videography). In addition, extensive surveys and censuses were taken of colonies to record colony productivity, dates of nest initiation and first worker emergence, usurpation and parasitism.¶There was no evidence that P. dominulus is negatively impacting P. fuscatus through direct, agonistic encounters. However, P. dominulus is 4-5 times more productive than P. fuscatus, suggesting that P. dominulus is replacing P. fuscatus via exploitative competition. P. dominulus appears to have a number of advantages over P. fuscatus, including earlier production of workers, higher per capita foraging rates by queens and workers, higher queen survivorship, and lack of conspecific pressures. Nest site and/or prey availability may be limiting factors in the competition between the two species.     

Mutual assessment via visual status signals in Polistes dominulus wasps

Many animals use signals to assess the fighting ability of rivals and reduce the cost of aggressive competition. However, little is known about how an individual''s own quality influences their signal assessment decisions. Polistes dominulus wasps have visual signals of fighting ability that provide a good model for testing the dynamics of rival choice. We found that rival assessment behaviour was influenced by the advertised quality of the individual, their rivals, and the interaction between individual and rival quality. Individuals of high advertised quality were more likely to challenge rivals and individuals of low advertised quality were more likely to be challenged. However, when choosing among two rivals with different advertised quality, individuals did not simply choose the lower quality rival. Instead, they only preferred the lower quality rival when there was a small difference between their own advertised quality and that of their rivals. Individuals were not choosy when both rivals advertised relatively high or relatively low quality. Therefore, although P. dominulus facial patterns function as conventional signals of fighting ability that provide valuable information about their bearer''s behavioural strategy, there is substantial variation in signal responses based on the relative intensity of the senders'' and receivers'' signals.     

Visual signals of individual identity in the wasp Polistes fuscatus

Individual recognition is an essential component of interactions in many social systems, but insects are often thought incapable of the sophistication necessary to recognize individuals. If this were true, it would impose limits on the societies that insects could form. For example, queens and workers of the paper wasp Polistes fuscatus form a linear dominance hierarchy that determines how food, work and reproduction are divided within the colony. Such a stable hierarchy would be facilitated if individuals of different ranks have some degree of recognition. P. fuscatus wasps have, to our knowledge, previously undocumented variability in their yellow facial and abdominal markings that are intriguing candidates for signals of individual identity. Here, I describe these highly variable markings and experimentally test whether P. fuscatus queens and workers use these markings to identify individual nest-mates visually. I demonstrate that individuals whose yellow markings are experimentally altered with paint receive more aggression than control wasps who are painted in a way that does not alter their markings. Further, aggression declines towards wasps with experimentally altered markings as these novel markings become familiar to their nestmates. This evidence for individual recognition in P. fuscatus indicates that interactions between insects may be even more complex than previously anticipated.     

Nourishment affects colony demographics in the paper wasp Polistes metricus

Abstract  1. Colony survivorship and numbers of nest cells, pupae, and adult females were monitored throughout the nesting season for a cohort of 78 colonies of the paper wasp Polistes metricus Say. Thirty-nine colonies received a twice-weekly nourishment supplement of honey during pre-emergence and early emergence phases of the colony cycle; 39 colonies were unsupplemented controls.
2. Colony survivorship was unaffected by the supplemental nourishment. Loss of colonies to predation differed among three sites but was unaffected by supplementation.
3. Honey-supplemented colonies constructed more nest cells than did control colonies but this effect was not expressed until after supplementation had ceased.
4. Honey-supplemented colonies produced more pupae than did control colonies but the number of adult females at nests did not differ between supplemented and control colonies. Because honey-supplemented colonies had more offspring but fewer of them remained as workers at the nest, honey supplementation led to a lower frequency of workers and corresponding higher frequency of reproductives than in control colonies.
5. In a second year of study, colony survivorship and numbers of nest cells, pupae, and adult females were monitored from late pre-emergence until the end of the nesting season for a cohort of 32 colonies of Polistes metricus . In 16 colonies, trophallactic saliva was taken from final-instar larvae on nine dates in the late pre-emergence and early emergence periods; 16 colonies served as controls.
6. Saliva-diminished colonies had lower survivorship, fewer nest cells, fewer pupae, and fewer adult females at the nest than did control colonies.
7. These results show that variation in nourishment in the early to mid phases of the colony cycle can have significant effects on the subsequent colony demographics of Polistes metricus paper wasps.     

Thermoregulation in the primitively eusocial paper wasp, Polistes dominulus

Regulation of wing muscle temperature is important for sustaining flight in many insects, and has been well studied in honeybees. It has been much less well studied in wasps and has never been demonstrated in Polistes paper wasps. We measured thorax, head, and abdomen temperatures of inactive Polistes dominulus workers as they warmed after transfer from 8 to ~25°C ambient temperature, after removal from hibernacula, and after periods of flight in a variable temperature room. Thorax temperature (T _th) of non-flying live wasps increased more rapidly than that of dead wasps, and T _th of some live wasps reached more than 2°C above ambient temperature (T _a), indicating endothermy. Wasps removed from hibernacula had body region temperatures significantly above ambient. The T _th of flying wasps was 2.5°C above ambient at T _a = 21°C, and at or even below ambient at T _a = 40°C. At 40°C head and abdomen temperatures were both more than 2°C below T _a, indicating evaporative cooling. We conclude that P. dominulus individuals demonstrate clear, albeit limited, thermoregulatory capacity.     

Experimental Changes of Hierarchical Rank in Polistes dominulus Christ Foundresses

Behavioural profiles of Polistes dominulus foundresses were studied after changes of hierarchical rank induced by transferring wasps between trigynous associations. Females were ranked on the basis of postures adopted in dyadic encounters, while time spent by individuals on 8 behavioural items was recorded and compared. A multivariate analysis showed that behavioural profiles depended mainly on the wasps' current rank. The previously held rank had little effect on the behaviour of females concurrently having beta rank, whereas some differences were observed among alpha females depending on their previous rank. Alphas that were previously betas spent more time at the nest, but were less active there than inveterate alphas. The profile characteristics of alpha rank seem to take longer to acquire than the beta profile. It is suggested that adopting the profile characteristic of a given rank may involve first occupying the territory consisting of the nest, secondly gradually producing appropriate responses to the various stimuli emanating therefrom, and thirdly, undergoing specific physiological changes.     

The social parasite wasp Polistes atrimandibularis does not form host races

Parasites that exploit the parental behaviour of several host species may be selected to form distinct host-specific genetic lineages. This process is well documented in bird brood parasites, but not in insect social parasites. Polistes atrimandibularis is the only paper-wasp social parasite known to exploit four host species. It does not form genetically distinct host races according to analyses based on microsatellite loci. Also, there were no size-matching between parasites and host species. Instead, P. atrimandibularis queens seemed to be successful as parasites in this population only when they originated from nests of P. dominulus, the largest species. The other host species are a sink for P. atrimandibularis since adult females emerging from those nests appear too small to usurp colonies themselves. Traits that may help P. atrimandibularis infiltrate multiple species may include its nonaggressive usurpation tactics and its ability to acquire host cuticular hydrocarbon recognition labels.     

闽东约马蜂的生物学习性观察

约马蜂PolistesjokanamaeRadoszkowski是一种习见的社会性天敌昆虫。研究表明约马蜂在闽东地区于4月中旬觅址筑巢,历经40d建成31~40个巢房的小巢。约马蜂1年发生2代,第1代蜂于5月下旬开始羽化,7月初蜂巢拥有职蜂可达30只,每只职蜂日均外勤达14次,群体进入快速增长期;第2代蜂8~9月间出现,雄蜂所占比例超过1/3,群体进入鼎盛期。第2代雌蜂与雄蜂交尾后于11月陆续离巢越冬。幼体发育历期28~37d,与外界气温密切相关,随温度升高而缩短。文中还提出计算幼体发育历期的方法。