Chemical signatures of egg maternity and Dufour's gland in Vespine wasps

Cuticular hydrocarbons (CHCs) are often used in the chemical communication among social insects. CHCs can be used in nestmate recognition and as queen pheromones, the latter allows the regulation of the reproductive division of labor. In the common wasp Vespula vulgaris, CHCs and egg-marking hydrocarbons are caste-specific, being hydrocarbon queen pheromones and egg maternity signals. Whether these compounds are conserved among other Vespinae wasps remains unknown. Queens, virgin queens, reproductive workers, and workers belonging to four different wasp species, Dolichovespula media, Dolichovespula saxonica, Vespa crabro, and Vespula germanica, were collected and studied. The cuticular hydrocarbons, egg surface, and Dufour's gland composition were characterized and it was found that chemical compounds are caste-specific in the four species. Quantitative and qualitative differences were detected in the cuticle, eggs, and Dufour's gland. Some specific hydrocarbons that were shown to be overproduced in the cuticle of queens were also present in higher quantities in queen-laid eggs and in their Dufour's gland. These hydrocarbons can be indicated as putative fertility signals that regulate the division of reproductive labor in these Vespine societies. Our results are in line with the literature for V. vulgaris and D. saxonica, in which hydrocarbons were shown to be conserved queen signals. This work presents correlative evidence that queen chemical compounds are found not only over the body surface of females but also in other sources, such as the Dufour's gland and eggs.