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).     

Mating structure and genetic relatedness among gynes in the primitively eusocial wasp Polistes snelleni (Hymenoptera: Vespidae)

Mating structure and genetic relatedness among gynes (potential reproductive females) of the paper wasp Polistes snelleni were investigated using DNA microsatellite markers. All colonies had one foundress inseminated by a single male, and no sign of inbreeding was detected. The mean genetic relatedness among gynes was 0.734 ± 0.028 (SE), which is not significantly different from the expected value of 0.75 for full sisters.     

A role of the Dufour's gland in the dominance interactions of the paper wasp,Polistes fuscatus (Hymenoptera: Vespidae)

The Dufour's gland of the paper wasp, Polistes fuscatus,is a source of the cues used by dominant females to recognize the eggs laid by subordinates or nonnestmates on pre (worker)-emergence nests. When dominant wasps were presented with an egg covered with either (1) the Dufour's gland extract of a subordinate cofoundress, (2) the extract of an egg from the same subordinate, or (3) the solvent alone, the dominant female destroyed and replaced the eggs covered with the Dufour's extract significantly more frequently than the other eggs. Eggs with the extract of a nonnestmate's Dufour's gland were also eaten significantly more frequently than those with the solvent. Given similar choices, subordinates did not destroy any eggs. The Dufour's gland appears to have little or no role in communicating dominance directly among aggressively interacting cofoundresses.     

Comparison of intraspecific nest usurpation between two haplometrotic paper wasp species (Hymenoptera: Vespidae:Polistes)

Intraspecific nest usurpation by foundresses was studied in 2 haplometrotic (solitary founding) species of different subgenera,Polistes (P.) riparius andP. (Polistella) snelleni, in areas where they cohabited. The overall probability for a nest to be usurped by a foreign foundress during the season was about twice as large inP. snelleni as inP. riparius. In both, however, probability of usurpation was largest on late pre-emergence nests, or in late June and early July. InP. riparius, all the usurpers of known origins were those foundresses that had lost their pre-emergence nests to destruction probably by some vertebrates; inP. snelleni, some usurpers had the same history as above, while the others had lost many of all larvae to predation by unknown agents before worker emergence. Usurpers of both species destroyed eggs and younger larvae to much greater extents than older larvae or pupae, and they produced fewer numbers of reproductives in comparison with non-usurping foundresses. We concluded that usurpation behavior has been maintained despite its relatively low productivity because renesting would lead to even lower or no reproductive production.     

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.

     

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.     

Worker reproduction and related behavior in orphan colonies of a Japanese paper wasp,Polistes jadwigae (Hymenoptera,Vespidae)

Worker reproduction and related behavior in 2 orphan colonies ofPolistes jadwigae, one of which had been maintained by a queen and 5 artificially introduced alien workers, were observed. After the queen loss, a dominance hierarchy was established among workers, and several workers laid eggs without physical interference from other workers. Only males emerged from worker-laid eggs, however, a few new queens were produced from queen-laid eggs. Investment sex ratio of queenright (=normal) colonies (0.27) fell between the 2 theoretical values, corresponding to worker control (0.20 or 0.18) and queen control (0.48 or 0.46) of the sex ratio, both being calculated by considering the excess of males produced in the orphan colonies.     

Post‐hibernation ovary development in queens of the Japanese giant hornet Vespa mandarinia (Hymenoptera: Vespidae)

Ovary contents and insemination status were examined in overwintered queens of Vespa mandarinia that were collected using bait traps in Ibaraki Prefecture, eastern Japan. Catches in the traps occurred from late April to early July in 1999, though they were few or rather sporadic in and after June. Fertilization rates were 100% in 1999, and 93% in 1998 when a preliminary sampling was made. While the ovary index (number of eggs with size equal to or larger than adjacent nurse cells) of queens caught on the first few collection dates was small, it rapidly increased up to late May. Generalized linear model analyses showed that the ovary index depended both on collection date and the size (head width) of the queens. Mature eggs were almost absent in their ovaries before early May, whereas more than 70% of the queens had one or more mature eggs on and after May 10, suggesting the onset of nesting in early May.     

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.     

Effects of female body size and timing of nest foundation on the reproduction of the Japanese paper wasp,Polistes jadwigae Dalla Torre (Hymenoptera: Vespidae)

Females in hibernation site (FH) were significantly larger than foundresses (FO), suggesting that larger FH were less successful in founding their nest. Body size of FO did not correlate with two nest characters, i.e., the number of cells at pupal stage (CP) and the timing of nest foundation (DP). However, CP negatively correlated with DP in 2 of 3 studied years, suggesting that foundress who founded her nest earlier than others tended to construct larger number of cells irrespective of her body size.     

Social behavior and brood decline in reproductive-phase colonies ofBelonogaster petiolata (Degeer) (Hymenoptera: Vespidae)

Colonies ofBelonogaster petiolata in Gauteng (South Africa) produced reproductive offspring (gynes and males) in late January and early February of each nesting season; their appearance was associated with a decline in worker and brood numbers. Brood decline could commence in the presence of a dominant, reproductively active queen, and loss or removal of the queen was not followed directly by cessation of nest growth and brood care. An older worker usually took over the α-position in queenless colonies. Several factors appear to contribute to brood decline and, ultimately, termination of the colony cycle in this species. These include (1) cessation of the supply of solid food to colonies (and particularly their larvae) during the reproductive phase, (2) a decrease in the worker/larva ratio during the latter phase due to the progressive loss of workers, (3) increasing number of gynes and males, and (4) an adult priority over food reception from foragers.     

Demography of the Okinawan eusocial wasp Ropalidia fasciata (Hymenoptera: Vespidae) II. Effects of foundress group size on survival rates of colonies and foundresses, and production of progeny

Using demography data for the primitively eusocial wasp Ropalidia fasciata collected at 10 survey stations over 5 years, the effects of foundress group size (FGS) on colony survival rate and production of progeny were examined. The distribution pattern for the frequency of nests established by different numbers of foundresses fit a 0‐truncated negative binomial distribution. The rate of nest failure up to the beginning of June decreased with FGS, and colony survival rate up to June and September increased with FGS. Although there were large variations among stations and years, the survival rate of colonies established by a single foundress (haplometrotic colonies) was significantly lower than that of colonies established by two or more foundresses (pleometrotic colonies). The number of new adults that emerged per colony up to the end of July increased with FGS, but there was no significant correlation between number of new adults per foundress and FGS. The number of potential foundresses produced per colony tended to increase with FGS, but there was no significant difference among the values produced per foundress for the three FGS categories. The percentage parasitism by an ichneumon parasitoid, Arthula formosana, tended to be higher in colonies established by a small number of foundresses. The relation between FGS and the productivity of the new foundresses was not statistically significant, suggesting that independent founding may be a better strategy for future subordinate foundresses. However, the long colony life span (mean 100 days, maximum 240 days) as compared with the shorter life span of foundresses (40 or 50 days) may be a good condition for the coexistence of many egg‐layers in a colony.     

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.     

Rank integration in dominance hierarchies of host colonies by the paper wasp social parasite Polistes sulcifer (Hymenoptera, Vespidae)

In multiple-foundress nests of the wasp Polistes dominulus, dominance hierarchies are established among foundresses, and only the dominant (=alpha) individual lays eggs. The alpha female can be distinguished from subordinate females and workers on the basis of the proportions of some hydrocarbons present on the cuticle, suggesting that chemical signaling of her reproductive status could occur. P. dominulus is also the host species of the obligate social parasite Polistes sulcifer. After aggressively usurping host colonies and behaviorally replacing the host alpha female, parasites are characterized by a change in the proportions of their cuticular hydrocarbons to match that of the host cuticular profile at both species and colony levels. In the current study, we demonstrate that P. sulcifer queens also modify their cuticular hydrocarbon proportions after usurpation to match that of the host alpha female. Parasite females, therefore, acquire the dominant rank in host colonies both reproductively and chemically by mimicking the typical alpha profile of the host. Parasite females were not able to fully inhibit ovary development in host foundresses, and 10 days after usurpation, parasites, alpha and beta foundresses show similar chemical profiles and ovarian development.     

Circulating hemocytes from larvae of the paper wasp Polistes dominulus (Hymenoptera, Vespidae)

Circulating hemocytes from larval stages of the paper wasp Polistes dominulus were characterized by light and transmission electron microscopy. Three types were identified: prohemocytes, plasmatocytes and granulocytes. The first two are agranular cells while the latter present typical cytoplasmic inclusions called granules. Plasmatocytes differ from prohemocytes being larger, showing lower nucleus/cytoplasm ratio and they possess many phagolysosomes. The substantial uniformity of most subcellular features and the presence of "intermediate forms" support the "single-cell theory" i.e., there is only one cell line that originates from the prohemocyte and leads to the granular cell passing through the plasmatocyte. This hypothesis seems to be confirmed by functional tests. Indeed, most part of cells adheres to the glass and is able to phagocytize fluorescent microspheres.     

Dispersion distance of queens from natal sites in the two haplometrotic paper waspsPolistes riparius andP. snelleni (Hymenoptera: Vespidae)

Dispersion capabilities of new queens were studied in the two haplometrotic paper wasps Polistes riparius and P. snelleni. New queens were marked on the nests in the late summer and located in the next spring. Dispersion distances greatly varied among queens: although a large part of recovered queens nested in close proximity to their natal sites, some did disperse over 100–300 m. This suggests that queens' emigration from and immigration into the censused areas occurred to a substantial extent. On the whole, these species exhibited a weaker “philopatric” tendency than those so far studied for dispersion distance, and seem to have the potential for a long-distance dispersion.     

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.