Notes on the nest of the social wasp Pseudopolybia langi (Hym., Vespidae, Polistinae)

Abstract Detailed descriptions of the architecture of Pseudopolybia langi nests are presented for the first time. Structural variations in the arrangements of nest parts are described and compared with features observed in other species of Pseudopolybia and other epiponine genera.

Metapolybia araujoi, a new species of swarming social wasp from the Brazilian Amazon rainforest (Vespidae: Polistinae)

Abstract A new species of Metapolybia, collected in Pará State, Brazil, by Adolph Ducke, in 1902, is described and comparative remarks are given.

Nectarinella manauara, new species and record of the genus from Brazilian Amazonia (Hymenoptera, Vespidae, Polistinae)

ABSTRACT Nectarinella manaura sp. nov. is described, representing the first record of the genus from Brazilian Amazonia. Its description raises richness for Nectarinella from two to three species, and extends the range of characteristics for the genus, especially in terms of body size and color patterns. Discovery of the new species may shed new light into the knowledge of phylogenetic relationships between Nectarinella and other closely related genera.

An adaptive view of caste differentiation in the neotropical wasp Polybia (Trichothorax) sericea Olivier (Hymenoptera: Vespidae)

The tribe Epiponini comprehends the swarm-founding Neotropical wasps, with several species endemic to Brazil, which are extremely important in studies of social evolution of wasps. The Epiponini diverge in several ways from the definitions of high eusociality, since caste syndromes range from species without morphological caste differentiation to those with complete caste dimorphism, and all species are polygynous. Frequently, indirect studies based on morphometry and physiology are the only solutions to collect data regarding the natural history and caste system in this tribe, since most species are extremely aggressive and build enveloped nests, usually in places of difficult access. We analyzed morphological parameters in seven colonies of the Epiponini species Polybia (Trichothorax) sericea Olivier in different phases of colonial development. Nine body variables were taken and females were classified according to their ovary development and spermathecal contents. The results showed that caste differences in this species are based on a contrast among variables: queens have larger mesosoma and abdomen, but are smaller in head width and wing length. These results suggest that morphological caste differentiation in this species is based mainly on body shape. We considered this combination of characters as being adaptive. We also showed that caste differences varied according to the colony cycle, with more conspicuous differences when queen number is reduced.

The acceptance rate of young wasps by alien colonies depends on colony developmental stages in the swarm-founding wasp, Polybia paulista von ihering (Hymenoptera: Vespidae)

In social insects, newly emerged individuals learn the colony-specific chemical label from their natal comb shortly after their emergence. These labels help to identify each individual's colony of origin and are used as a recognition template against which individuals can discriminate nestmates from non-nestmates. Our previous studies with Polybia paulista von Ihering support this general pattern, and the acceptance rate of young female and male wasps decreased as a function of their age. Our study also showed in P. paulista that more than 90 percent of newly emerged female wasps might be accepted by conspecific unrelated colonies. However, it has not been investigated whether the acceptance rate of newly emerged female wasps depends on colony developmental stage of recipient colonies. We introduced newly emerged female wasps of P. paulista into different colony developmental stags of recipient colonies, i.e., worker-producing and male-producing colonies. We found that the acceptance rate of newly emerged female wasps by alien colonies was pretty lower by male-producing colonies than worker-producing colonies. This is the first study to show that the acceptance rate of young female wasps depends on stages of recipient colonies.

Nest thermoregulation in Polybia scutellaris (White) (Hymenoptera: Vespidae)

Polybia scutellaris (White) builds large nests characterized by numerous spiny projections on the surface. In order to determine whether or not the nest temperature is maintained because of homeothermic conditions of the nest individuals or otherwise, we investigated the thermal conditions within the nests built by P. scutellaris. We measured the temperature within active and abandoned nests. The temperature in the active nest was almost stable at 27°C during data collection, whereas the temperature in the abandoned nest varied with changes in ambient temperature. These results suggest that nest temperature was maintained by the thermogenesis of the individuals of the colony. This is the first report of nest incubation caused by thermogenesis of species of Polybia wasps.

Castes in the neotropical social wasp Leipomeles dorsata (Fabricius) (Hymenoptera: Vespidae): a window for workers achieving a new status in the colony

Morphometric studies performed in several species of Neotropical social wasps from the tribe Epiponini showed that in some species there are marked differences between castes, while other species present highly distinct castes with differences only in ovarian development. This work analyzed females from six colonies of the social wasp Leipomeles dorsata (Fabricius) in which queens (egglayers) and workers showed differences in ovarian development and coloration. We propose that wasps with developed ovaries (egglayers) and coloration similar to those of workers are possibly intermediates that obtained the status of queens in the colony.

An improved bait method for collecting hymenoptera, especially social wasps (Vespidae: Polistinae) / Método de armadilha melhorado para a coleta de hymenoptera, especialmente de vespas sociais (Vespidae: Polistinae)

In this work, an alternative method for the capture of neotropical social wasps is described, which may supplement or replace the procedures commonly used in wasp surveys. The method was tested in a seasonal semideciduous forest in the northwest of São Paulo State, collecting a larger number of species and a greater abundance of social wasps and of other Hymenoptera than other methods also used in the same area, namely Malaise traps, bottle traps and meat baits. The proposed method was adapted from Wille (1962) who used an attractive solution based on water and honey for bee attraction. In here, the attractive solution was based on water, salt and crystal sugar, and was effective in attracting bees and solitary wasps, but mainly social wasps, which is the group of interest for this report.

Neste trabalho é proposto método para a captura de vespas sociais neotropicais nos mais diferentes habitats e que pode substituir os métodos comumente utilizados em levantamentos faunísticos de curto prazo. O método foi inicialmente testado em um fragmento de floresta estacional semidecidual no Noroeste do estado de São Paulo, obtendo sucesso na coleta de vespas sociais e também de outros grupos de Hymenoptera. Coletou um número maior de espécies e também maior abundância do que outros métodos utilizados na mesma área, como armadilhas Malaise, garrafas-armadilha e iscas de carne. O método desenvolvido baseou-se na proposta de Wille (1962), que utilizou uma solução atrativa, composta por água e mel, para a coleta de abelhas. Neste trabalho, substituiu-se o mel por açúcar e adicionou-se sal, obtendo sucesso na atração não apenas de vespas sociais, mas também de abelhas e vespas solitárias.

Morphological caste studies in the neotropical swarm-founding Polistinae wasp Angiopolybia pallens (Lepeletier) (Hymenoptera: Vespidae) / Estudos morfológicos das castas da vespa Polistinae enxameadora neotropical, Angiopolybia pallens (Lepeletier) (Hymenoptera: Vespidae)

Neotropical swarm-founding wasps present polygynic colonies and a great variation in relation to caste differentiation, ranging from species in which queens and workers are similar in shape and size to those where variation in shape and size is conspicuous. Canonical discriminant analysis and Bonferroni t-test analysis on morphometric data collected from eight body parts of specimens from nine colonies of Angiopolybia pallens (Lepeletier) were undertaken as a step towards to a better understanding on caste differenciation in Epiponini. All specimens were dissected to verify the ovary developmental stage, and the spermatheca was removed to check for the mating status. Females were then grouped as queens (mated with developed ovaries), intermediates (virgin with developed ovaries) and workers (virgin with undeveloped ovaries). Even though differences were found for some measurements in seven out of the nine colonies evaluated, multivariate analysis (Wilks' lambda values) indicated castes could not be reliably distinguished only by morphology. We conclude that morphological differences among A. pallens castes are low or absent, reflecting a possible groundplan for the Epiponini, i.e. a post-imaginal pattern of caste differentiation.

As vespas neotropicais enxameadoras possuem colônias poligínicas e uma variação muito grande em relação à diferenciação das castas, desde espécies em que rainhas e operárias possuem formas e tamanhos semelhantes até aquelas em que grande diferença na forma e no tamanho são observados. Estudos morfométricos utilizando oito medidas corporais em nove colônias de Angiopolybia pallens (Lepeletier) foram realizados a fim de aumentar o conhecimento sobre diferenciação de castas em Epiponini, empregando-se análise canônica discriminante e teste t de Bonferroni. Os indivíduos foram dissecados para determinar o nível de desenvolvimento ovariano e as espermatecas foram removidas para verificar a ocorrência de inseminação e assim definir os três grupos de fêmeas: rainhas (ovários desenvolvidos e espermateca fecundada), intermediárias (ovários desenvolvidos e espermateca não-fecundada) e operárias (ovários não-desenvolvidos). Apesar de serem encontradas diferenças significativas para algumas medidas em sete das nove colônias, a análise multivariada (lambda de Wilks) mostrou que as castas são de difícil distinção apenas pela morfologia. É possível concluir que diferenças morfológicas entre castas de A. pallens são pequenas ou ausentes, o que reflete o plano basal para os Epiponini, i.e. padrão pós-imaginal de diferenciação castas.