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

Abstract

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.

Resource limitation, intra‐group aggression and brain neuropeptide expression in a social wasp

“…At the conclusion of experimentation, we dissected the abdomens of 24 workers from each of the diet treatments to remove organs, leaving the fat body adhered to the cuticle. We removed ovaries and scored ovarian development in a manner similar to the protocol used for honeybees (Velthuis, 1970) and other polistine wasp studies (Daugherty et al., 2011; Desuó et al., 2011; Gobbi et al., 2006; Walton et al., 2020; see Table S1). Next, we weighed the abdomens using a balance (Mettler AE 100) to the nearest 0.01 mg, and extracted lipids in 2:1 chloroform: methanol.…”