MORPHOLOGICAL CASTE DIFFERENCES IN POLYBIA AEQUATORIALIS (HYMENOPTERA: VESPIDAE: POLISTINAE: EPIPONINI), A SOCIAL WASP OF THE HIGHLANDS OF COSTA RICA

Many aspects of the biology and organization of Neotropical social wasps in the highlands are unknown. Polybia aequatorialis is a highland wasp of Costa Rica distributed between 1, 150 and 3,200 m in altitude, and little information on this species is recorded. We investigated the size of a colony of P. aequatorialis in the Cerro de la Muerte region of Costa Rica, and studied the morphological differences between queens and workers. Measures were taken from 248 reproductive and non-reproductive females, and caste differentiation was analyzed by Discrimination Function Analysis. We did not find a highly pronounced caste distinction in P. aequatorialis, even though ANOVA showed that queens and workers differed in all morphometric measures. The morphological differences between the reproductive and non-reproductive females probably results from a developmental switch, which is a characteristic caste syndrome of Polybia.

Morphological caste differences in the neotropical swarm-founding polistine wasp, Brachygastra lecheguana (Hymenoptera : Vespidae, Polistinae, Epiponini)

Morphological caste differences and ovary conditions were analyzed in colony of Brachygastra lecheguana. The results indicate the presence of individuals with ovary development but uninseminated (intermediates). In addition, these females were similar in morphology to workers, suggesting that, in this case, intermediates are ovary-developed workers. Queens were morphologically larger than workers and intermediates in some characters and smaller in others. Multivariate analysis showed that queens were highly distinct. These results indicate that castes are pre-imaginally determined in B. lecheguana.

MORPHOLOGICAL CASTE DIFFERENCES IN POLYBIA AEQUATORIALIS (HYMENOPTERA: VESPIDAE: POLISTINAE: EPIPONINI), A SOCIAL WASP of THE HIGHLANDS of COSTA RICA

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caste Differences in Polybia emaciata, a Mud-Nesting Eusocial Wasp (Hymenoptera: Vespidae), that Bear on Pre-Imaginal Determination but not Size Differences

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caste differences in Pseudopolybia compressa (Hymenoptera: Vespidae: Polistinae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphological caste differences and non-sterility of workers in Brachygastra augusti (Hymenoptera, Vespidae, Epiponini), a neotropical swarm-founding wasp

Morphological caste differences and ovary conditions were analyzed in four colonies of Brachygastra augusti collected in different stages of the colony cycle. Differences between castes are distinct suggesting pre-imaginal determination. Many intermediates (non-inseminated ovary-developed females) were found. Because these intermediate females were morphologically similar to workers, it is suggested that they are young ovary-developed workers. Because there is a more evident overlap between queens and workers in the colony in pre-emergence of workers stage, and in three colonies in latter stages, especially in worker-production colonies, it is suggested that smaller queens are probably less viable than larger queens as observed in previously studied epiponines.

Non-allometric caste differences in Agelaia vicina (Hymenoptera, Vespidae, Epiponini)

Non-allometric and clear-cut caste dimorphism were found in two colonies of the social wasp Agelaia vicina. Such type of allometry was previously recorded in the Epiponini and its origin is pre-imaginally determined as in the other analysed species which present caste dimorphism. Multivariate analyses evidenced that the most intercastes discriminant characters were found in the metasoma and mesosoma while head differences were slight. Although queens were characterized by marked ovary development and insemination, the presence of some uninseminated queens was detected in one of the analysed colonies.

Morphological and physiological caste differences in Synoeca cyanea (Hymenoptera, Vespidae, Epiponini) according to the ontogenetic development of the colonies

Morphological caste differences in different stages of the biological cycle in Synoeca cyanea were not distinct. Females presented a gradual sequence in ovarian development from filamentous ovarioles to well developed ones with the presence of intermediates, with shorter ovaries than queens, which can be present or not according to the stage of colonial development. Such data suggest that access to the reproductive status would only be possible in some intervals of colonial development.

Caste differences in Polybia ematiata, a mud-nesting eusocial wasp (hymenoptera: Vespidae), that bear on pre-imaginal determination but not size differences

The Epiponini is a group of social wasps living in polygynic societies. The caste dimorphism varies from incipient to well distinct. Morphometric analyses on twelve body parts and ovarian development of Polybia emaciata Lucas 1879, were used to estimate the level of caste differentiation in seven colonies. Physiologic differences were found. Among queens the ovaries were inseminated and presented as highly developed; in intermediate females, ovaries were slightly developed and uninseminated, and for the workers the ovaries were not developed or inseminated. In addition, the coloration of the mesosoma and metasoma were darker in workers and intermediates. Morphometric analysis evidenced slight morphological differences. Even though body proportions were not enough to discriminate castes, the fifth sternite of the gaster had important characters that were able to differentiate queens from workers and intermediates. We propose that P. emaciata presents a case of pre-imaginal caste determination, which is not strictly based on size.

Morphological caste differences in three species of the Neotropical genus Clypearia (Hymenoptera: Polistinae: Epiponini)

Clypearia is a rare genus of swarm-founding Neotropical wasp whose biology is very little known. Morphological castes differences, condition of ovaries, relative age, and color pattern differences were analyzed in three species of Clypearia. Physiological differences and low morphometric differentiation between queens and workers were present in all species studied, indicating that these species are characterized by physiological caste only. We suggest that caste determination in the three Clypearia species studied is postimaginal. © 2010 Giovanna Tocchini Felippotti et al.

Caste-specific cuticular lipids in the stingless bee Friesella schrottkyi

While a queen control pheromone complex that inhibits worker ovary development has been described for honey bees, no comparable control pheromones have been identified for their sister group, the stingless bees. The aim of the present work was to search for possible control pheromones in the stingless bee Friesella schrottkyi. No volatile substances were found in the heads of queens that might serve as queen control pheromones. On the other hand, distinct differences were found between the cuticular substances of queens and workers. The major hydrocarbons were different between the two castes, and while queens contained methyl-branched alkanes and no unsaturated hydrocarbons, workers contained alkenes and alka-dienes but no methyl branched hydrocarbons. Colonies deprived of a queen produced laying workers. Differences were observed in the cuticular patterns of laying workers and workers from a queen controlled colony.

Representational Difference Analysis (RDA) reveals differential expression of conserved as well as novel genes during caste-specific development of the honey bee (Apis mellifera L.) ovary

In highly eusocial insects, such as the honey bee, Apis mellifera, the reproductive bias has become embedded in morphological caste differences. These are most expressively denoted in ovary size, with adult queens having large ovaries consisting of 150-200 ovarioles each, while workers typically have only 1-20 ovarioles per ovary. This morphological differentiation is a result of hormonal signals triggered by the diet change in the third larval instar, which eventually generate caste-specific gene expression patterns. To reveal these we produced differential gene expression libraries by Representational Difference Analysis (RDA) for queen and worker ovaries in a developmental stage when cell death is a prominent feature in the ovarioles of workers, whereas all ovarioles are maintained and extend in length in queens. In the queen library, 48% of the gene set represented homologs of known Drosophila genes, whereas in the worker ovary, the largest set (59%) were ESTs evidencing novel genes, not even computationally predicted in the honey bee genome. Differential expression was confirmed by quantitative RT-PCR for a selected gene set, denoting major differences for two queen and two worker library genes. These included two unpredicted genes located in chromosome 11 (Group11.35 and Group11.31, respectively) possibly representing long non-coding RNAs. Being candidates as modulators of ovary development, their expression and functional analysis should be a focal point for future studies. (C) 2011 Elsevier Ltd. All rights reserved.

Differential expression of hypoxia pathway genes in honey bee (Apis mellifera L.) caste development

Diphenism in social bees is essentially contingent on nutrient-induced cellular and systemic physiological responses resulting in divergent gene expression patterns. Analyses of juvenile hormone (JH) titers and functional genomics assays of the insulin-insulin-like signaling (IIS) pathway and its associated branch, target-of-rapamycin (TOR), revealed systemic responses underlying honey bee (Apis mellifera) caste development. Nevertheless, little attention has been paid to cellular metabolic responses. Following up earlier investigations showing major caste differences in oxidative metabolism and mitochondrial physiology, we herein identified honey bee homologs of hypoxia signaling factors, HIF alpha/Sima, HIF beta/Tango and PHD/Fatiga and we investigated their transcript levels throughout critical stages of larval development. Amsima, Amtango and Amfatiga showed correlated transcriptional activity, with two peaks of occurring in both queens and workers, the first one shortly after the last larval molt and the second during the cocoon-spinning phase. Transcript levels for the three genes were consistently higher in workers. As there is no evidence for major microenvironmental differences in oxygen levels within the brood nest area, this appears to be an inherent caste character. Quantitative PCR analyses on worker brain, ovary, and leg imaginal discs showed that these tissues differ in transcript levels. Being a highly conserved pathway and linked to IIS/TOR, the hypoxia gene expression pattern seen in honey bee larvae denotes that the hypoxia pathway has undergone a transformation, at least during larval development, from a response to environmental oxygen concentrations to an endogenous regulatory factor in the diphenic development of honey bee larvae. (C) 2010 Elsevier Ltd. All rights reserved.

Overview of Caste Differentiation in the Polistinae, Emphasizing the Neotropical Swarm-Founding Polistinae (Hymenoptera, Vespidae, Epiponini)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)