Isolation and characterization of 10 microsatellite loci in the paper wasp Polistes rothneyi (Hymenoptera; Vespidae)

We developed 10 polymorphic microsatellite loci for the Japanese paper wasp Polistes rothneyi using the magnetic particle method. Eight of the 10 loci tested were highly polymorphic, having four to eight alleles in P. rothneyi with an expected heterozygosity of 0.60–0.75. They also appeared to be applicable to other related species such as Polistes jokahamae. These loci can be used to study parameters concerning genetic relatedness such as worker reproduction and kin structure.     

Colony founding in the primitively eusocial wasp, Ropalidia marginata (Hymenoptera: Vespidae)

Abstract.

• 1 In a 16-month study in Bangalore, India, about 35% of the newly founded colonies of Ropalidia marginata were single foundress colonies and the remainder were multiple foundress colonies with two to twenty-two individuals.
• 2 Larger colonies did not have a significantly higher per capita productivity, did not produce significantly heavier progeny and did not produce them significantly faster than smaller colonies did.
• 3 Predation by the hornet Vespa tropica appeared to be independent of group size.
• 4 Single foundress colonies failed more often but not often enough to make them have a lower average per capita productivity, compared to multiple foundress colonies.
• 5 Some of the advantages of multiple foundress associations came from the greater predictability of their attaining the mean per capita productivity, the relatively lower rates of usurpation experienced by them compared to single foundress colonies, and the opportunities provided by queen turnovers for workers to become replacement queens and gain direct individual fitness.

     

Mating frequency and genetic relatedness of workers in the hornet Vespa analis (Hymenoptera: Vespidae)

Mating frequency of Vespa analis queens and the genetic relatedness of their workers was analyzed by DNA microsatellite genotyping. Of 20 colonies studied, 18 had a queen inseminated by a single male and two had queens each inseminated by two males. The estimated effective number of matings was 1.05 ± 0.037 (mean ± SE), with 75–85% of the offspring of the two multiply mated queens sired by a single male. The pedigree relatedness between nestmate workers averaged over the 20 colonies was estimated to be 0.74 ± 0.008, almost identical to the predicted value of 0.75 for colonies headed by a singly mated queen. Multiple matrilines; that is, the presence of workers not related to the current queens, were detected in six colonies, suggesting that queen replacement occurred via usurpation of the founding queens in these six colonies. These results demonstrate that the kin structure of V. analis is similar to that reported in other vespid species.     

Foundress behaviors and interactions in polygynous colonies of the haplometrotic Japanese paper wasp Polistes snelleni (Hymenoptera: Vespidae)

Only two out of 959 pre‐emergence colonies of the paper wasp Polistes snelleni de Saussure surveyed between 1989 and 1996 in Sapporo, northern Japan, were found to be two‐foundress colonies, and the others were single‐foundress colonies. The two foundresses in one of the two colonies showed neither aggressive dominance behavior nor clear division of labor between them during a total of approximately 30 h in the first half of the pre‐emergence stage. Although both of the foundresses foraged for pulp and laid eggs, only one foundress foraged for prey and delivered it to the other.     

Polymorphic microsatellite loci for the Japanese paper wasp,Polistes chinensis antennalis (Hymenoptera: Vespidae)

We isolated 13 microsatellite markers for the Japanese paper wasp Polistes chinensis antennalis. Null alleles were ruled out in the loci because we could detect polymerase chain reaction products for 578 haploid males. Our results indicate that these markers are excellent tools for the analysis of pedigrees within colonies for species with a complicated pedigree structure due to worker reproduction (male production by workers in queen‐right colonies).     

Reproductive and worker castes in the primitively eusocial wasp Belonogaster petiolata (DeGeer) (Hymenoptera: Vespidae): evidence for pre-imaginal differentiation

Until recently, morphological differences between castes in independent-founding polistine wasps were considered absent. This paper investigates the extent of morphological and physiological differences between reproductive (foundress and gyne) and worker castes of Belonogaster petiolata, and tests the hypothesis that caste differentiation in this species occurs pre-imaginally.Foundresses were significantly larger than workers, to the extent that foundress/worker ratios were comparable with those between queens and workers in some swarm-founding Polistinae. Early emerging workers were small, but body size increased over the colony cycle such that late-season workers were similar in size to gynes. In proportion to body size, workers possessed broader heads while foundresses and gynes had broader thoraces and gasters. All queens, 98% of subordinate foundresses, and 95% of over-wintering gynes were inseminated. Workers were never inseminated and lacked mature ovaries in colonies with active queens. However, in the absence of the queen (and other foundresses), 11% of workers developed mature ovaries. Ovarian size and fat content of foundresses and gynes was significantly greater than that of workers. The differences in external morphology and reproductive physiology between castes support the hypothesis that differentiation occurs pre-imaginally. However, imaginal factors, in particular social dominance of the queen, maintain the reproductive subordinance of workers.     

The role of larval nutrition in pre-imaginal biasing of caste in the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae)

Abstract.

• 1 When freshly eclosed females of the primitively eusocial wasp Ropalidia marginata (Lep.) are isolated, only about 50% of them build nests and lay eggs thereby suggesting a pre-imaginal biasing of caste.
• 2 Wasps that lay eggs take a very variable amount of time after eclosion to start doing so.
• 3 Females eclosing from nests where larvae are fed at a relatively higher rate are more likely to become egg-layers and are likely to take less time after eclosion to begin to lay eggs.
• 4 Thus, both forms of pre-imaginal biasing of caste, namely, differences in egg laying capacity and differences in the time taken to attain reproductive maturity, appear to be influenced by larval nutrition.

     

Behavioral role differentiation in the primitively eusocial waspBelonogaster juncea juncea (Hymenoptera: Vespidae)

With a view toward describing behavioral variability among individuals of the primitively eusocial speciesBelonogaster juncea juncea, we recorded the time-activity budget spent on five behavioral categories (foraging, building, feeding, inactivity, and reproduction) by 52 individuals belonging to four postemergence colonies. A principal-components analysis coupled with a hierarchical cluster analysis enabled us to discern four behavioral roles. The reproductive role is reserved to one individual (functional monogyny) and the workers’ role is differentiated into foragers, builders, and guards. The foragers are females that spend the most time (82.6% of their time) foraging, supplying the nest with prey load and liquid matter. The builders are individuals (with 41.5% of their time off the nest) that tend to bring pulp into the nest and then undertake building activities. The guards are those females that spend the most time (79.7% of their time) being inactive on the nest.     

西藏波密柑马蜂的筑巢习性（英文）

柑马蜂Polistes mandarinus在不同的环境中会利用植物材料制作各种不同的蜂巢。我们在2009年5-8月间观察研究了西藏自治区波密县的柑马蜂筑巢习性, 并收集62个蜂巢。柑马蜂利用植物纤维和树脂将它们的巢穴筑于当地居民的木屋檐下。收集的42个在用蜂巢中, 8月末平均拥有79.64±65.28个蜂房, 13.1±10.68个蜂蛹。20个弃用蜂巢中, 平均拥有12.95±3.99个蜂房。8月末, 成功的柑马蜂群拥有约80个个体。研究地的柑马蜂采取3种方式来筑巢, 但以第1种方式最为普遍。第1种筑巢方式筑造的蜂巢以两个蜂房连接巢柄, 结构最为稳定, 所以也应用最广, 后两种筑巢方式筑造的蜂巢均以一个蜂房连接巢柄, 是由于越冬雌蜂在找不到合适的筑巢材料时才采取的建巢方式。     

Genetic structure of an introduced paper wasp,Polistes chinensis antennalis (Hymenoptera,Vespidae) in New Zealand

Several eusocial wasps are prominent invaders to remote islands. The paper wasp Polistes chinensis antennalis is native to East Asia, was introduced to New Zealand in 1979 and has expanded its distribution there. This provides an excellent opportunity to examine the impacts of an initial bottleneck and subsequent expansion on genetic structure. We analysed and compared the genetic population structures of the native (Japan and South Korea) and invasive New Zealand populations. Although 94% of individuals had shared haplotypes detected across both populations, the remaining 6% had private haplotypes identified in only one of the three countries. The genetic variation at microsatellite loci was lower in New Zealand than in native countries, and the genetic structure in New Zealand was clearly distinct from that in its native range. Higher frequencies of diploid‐male‐ and triploid‐female‐producing colonies were detected in New Zealand than in the native countries, showing the reduction in genetic variation via a genetic bottleneck. At least two independent introductions were suggested, and the putative source regions for New Zealand were assigned as Kanto (central island) and Kyushu (south island) in Japan. Serial founder events following the initial introduction were also indicated. The estimated dispersal distance between mother and daughter in New Zealand was twice that in Japan. Thus, the introduction history of P. chinensis antennalis in New Zealand is probably the result of at least two independent introductions, passing through a bottleneck during introduction, followed by population expansion from the point of introduction.     

Queen succession in the primitively eusocial tropical waspRopalidia marginata (Lep.) (Hymenoptera: Vespidae)

Females of the primitively eusocial wasp Ropalidia marginata can be classified into three behavioral groups: Sitters, Fighters, and Foragers. It has been speculated that both Sitters and Fighters may be hopeful queens and that the Foragers may have little or no opportunities for direct reproduction. Here we show that in 9 of 12 queen-removal experiments where such a behavioral differentiation could be discerned, the individual that became a queen (the potential queen) was a Sitter in 6 cases, a Fighter in 2 cases, and a Forager in only 1 case. Although potential queens spent significantly more time absent from the nest and showed significantly higher rates of dominance behavior compared to the mean values for nonqueens in their colonies, they were intermediate with respect to all behaviors and age when compared to the range of values for nonqueens in their colonies. Potential queens were not necessarily the highest-ranking individuals among the nonqueens. The pattern of queen succession in this species appears to be quite different from the temperate pattern, where an old and active forager of high dominance rank is the potential queen. Although somewhat similar to the tropical pattern of a relatively younger female that has performed relatively little foraging being the potential queen, it is perhaps more accurate to describe the potential queens of R. marginata as unspecialized intermediates.     

Polymorphic microsatellite loci for the swarm-founding wasp Polybia paulista (Hymenoptera: Vespidae)

A polymorphic microsatellite locus was isolated and characterized from Polybia paulista, one of the most common polygynic, swarm‐founding social wasps in Brazil. Three other microsatellite loci for which the primer sets were originally developed in independent‐founding paper wasps also showed polymorphism in the size of amplification products in P. paulista.     

Genetic population structure of the paper wasp Polistes olivaceus (Hymenoptera: Vespidae) in Bangladesh

Dispersal triggers gene flow, which in turn strongly affects the ensuing genetic population structure of a species. Using nuclear microsatellite loci and mitochondrial DNA (mtDNA), we estimated the genetic population structure of the wasp Polistes olivaceus throughout Bangladesh. The level of population differentiation using nuclear markers (F _ST) appeared to be much lower than that estimated using mtDNA haplotype sequences (Ф_ST), even after correcting for effective population size differences between the two markers. These results suggest a philopatric tendency, in which gynes disperse less than males. We observed no isolation by distance among the study populations at either the nuclear or mtDNA level, suggesting nonequilibrium between gene flow and drift as a result of very frequent interpopulation movement. For the nuclear markers, an individual assignment test showed no genetically and geographically distinct groups. Instead, phylogenetic analyses as well as a minimum spanning network using mtDNA haplotypes consistently revealed two distinct lineages. The distribution of haplotypes indicated western populations with a single lineage and offered clear evidence for restricted gene flow across the Jamuna–Padma–Upper Meghna river system. Mismatch distributions exhibited a unimodal distribution, which along with a starlike haplotype network, suggested a population expansion in lineage I but not in lineage II. Overall, these results suggest that gene flow among populations of P. olivaceus was affected by both female philopatry and a major river system across Bangladesh.     

Unmated queens in the primitively eusocial waspRopalidia marginata (Lep.) (Hymenoptera: Vespidae)

Summary In the primitively eusocial tropical waspRopalidia marginata, five out of eleven colonies studied had an unmated female as their queen. In two colonies this was the case despite the presence of another mated individual in the colony. We found no detectable differences between colonies with unmated queens and those with mated queens. We argue that in species such asR. marginata, where intracolony relatedness is expected to be low and where sociality is likely to be maintained because several individuals have opportunities for direct reproduction in the future, individual selection is likely to override the good of the colony and lead to such phenomena as that of unmated queens.     

Absence of chemical alarm in a primitively eusocial wasp (Belonogaster petiolata,Hymenoptera: Vespidae)

Summary The hypothesis thatBelonogaster petiolata (fam. Vespidae) is able to communicate alarm chemically, using odours released with the venom, was tested in bioassays involving presentation of artificial targets to a wasp colony, simultaneously with crushed venom apparatuses. The odour of venom did not lower the threshold of attack and visual stimuli alone (particularly a black, moving object) were sufficient to release attack. Venom odour on a previously stung target probably does not play a role in focusing further attacks on such a target. The results therefore support the null hypothesis that a venom-based alarm pheromone is absent in this species.     

Demography of the Okinawan eusocial wasp Ropalidia fasciata (Hymenoptera: Vespidae) I. Survival rate of individuals and colonies, and yearly fluctuations in colony density

We conducted a series of demographic studies of the primitively eusocial wasp Ropalidia fasciata in Okinawa, a subtropical part of Japan, and found the following. The colony cycle of this wasp is annual, spanning from April to November or even December; this is longer than the colony cycles of other temperate polistine wasps so far reported. The survival rate of the marked foundresses was 40% to June, dropping to 1.4% by September. These survival rates are similar to other subtropical and tropical species. Most females that emerged in November were probably second generation adults (progeny of the original foundresses), which would participate in founding nests in the following spring. These facts indicate that R. fasciata in Okinawa is at least partially bivoltine. Survival of a nest to September was 10–20%; however, because a failed nest is often rebuilt, survival of the colony to September was as high as 50%. The mean number of new foundresses produced per foundress was 7.5, and their overwintering survival was 16%. Hence, a single foundress produced, on average, 1.2 progeny foundresses to the following year. Density dependence was shown in the rate at which the progeny foundresses were produced. These results explain the remarkable stability of nest densities from year to year in the area. The above results reveal that R. fasciata in Okinawa shares many demographic characteristics with other primitively eusocial wasps, particularly year‐to‐year stability of nest density and a long colony cycle.     

Genetic relatedness and population structure in the social wasp,Mischocyttarus mexicanus (Hymenoptera: Vespidae)

Summary In primitively eusocial wasps workers often retain the ability to become queens, so their continued performance in the worker role is partly dependent on elevated genetic relatedness between workers and the brood they rear. In colonies of the social wasp,Mischocyttarus mexicanus, workers were related to female pupae by 0.29±0.12, a value that is significantly below the full sister value of 0.75, but not significantly below 0.50, worker relatedness to daughters. Though individuals often build new nests within meters of their natal nest, there was no genetic population structure discernable among four nest clusters, or inbreeding of any kind.     

Dominance behaviour and regulation of foraging in the primitively eusocial wasp Ropalidia marginata (Lep.) (Hymenoptera: Vespidae)

Ropalidia marginata is a primitively eusocial, polistine wasp widely distributed in peninsular India. In spite of its primitively eusocial status, queens of R. marginata are surprisingly docile and behaviourally non-dominant (except during the first week or so of their careers as queens). Yet they successfully maintain reproductive monopoly throughout their careers, probably through the use of pheromones. Workers exhibit dominance-subordinate interactions but these behaviours are not involved in regulating reproductive competition among the workers because workers with high dominance ranks are not necessarily the ones who replace lost queens. We have speculated and provided correlational evidence before that dominance-subordinate interactions among the workers have been co-opted in this species for the workers to regulate each other's foraging. Here, we provide experimental evidence in support of the speculation, by reducing demand for food and showing that this results in a significant decrease in the frequency of dominance-subordinate interactions among the workers.     

Polistes dominulus (Hymenoptera: Vespidae) larvae possess their own chemical signatures

Social insects use cuticular hydrocarbons (CHCs) as recognition cues in a variety of social contexts, such as species and nestmate recognition. Discrimination of nestmates is an important requisite to avoid exploitation by unrelated individuals. In social wasps, use of CHCs in nestmate recognition has been demonstrated only among adults, whereas very little is known regarding brood recognition. We performed gas chromatography-mass spectrometry analyses of the CHCs of adults and larvae of the social wasp Polistes dominulus and found that larvae possess a characteristic chemical colony-specific pattern distinct from that of adults. Behavioural assays confirmed that these are recognized and discriminated by adults. Larval epicuticular substances are therefore sufficient for recognition of nestmate larvae by adults and demonstrate that wasps are able to discriminate between alien and nestmate larval odours.