Lack of caste discrimination by males during sexual context in a neotropical paper wasp

Abstract

AbstractPotential mates often exhibit strong variation in reproductive quality, so the choice for the best sexual partner is generally adaptive. However, its adaptive value diminishes in cases where potential mates are similarly fit or when mate choice is too costly, leading mate choice to be unusual or absent. “Primitively eusocial” insects have flexible castes. Workers usually behave as “helpers,” but sometimes they mate and lay fertilized eggs. Despite worker totipotence, direct reproduction is, overall, higher in queens. Males of the temperate paper wasp Polistes dominula are able to discriminate castes, preferring gynes (= future queens) over workers, thus assuring more profitable mates. To our knowledge, no study has tested this ability in neotropical paper wasps. Here, we test the prediction that in the congeneric neotropical paper wasp Polistes versicolor, male sexual preference for gynes is unusual or absent. We perform laboratory paired mating trials in which a male was introduced to either a gyne or a worker. Caste assigned was confirmed by morphophysiological analysis. As predicted, male sexual interest was similar regardless of female caste. Conducting gas chromatography analysis, we demonstrated that queens and workers have distinct cuticular hydrocarbon profiles so caste‐related cues are available. We discuss the possibility that reduced differences in direct reproductive potential between castes and high costs of caste discrimination account for the absence of mate choice for gynes in P. versicolor males despite its occurrence in P. dominula. Thus, caste discrimination by males during sexual context is not so strict in species in which workers are able to mate and lay fertilized eggs.