Ropalidia marginata – a primitively eusocial wasp society headed by behaviourally non-dominant queens

摘要

Ropalidia marginata is a primitively eusocial polistine wasp widely distributed in peninsular India. As in most other primitively eusocial insects studied so far, colonies are headed by a single queen who monopolizes reproduction while the remaining female wasps in the colony function as sterile workers. Unlike in other species however, R. marginata queens are strikingly docile individuals who show little or no physical dominance. When such a behaviourally docile queen is removed from a colony, one of the remaining individuals becomes extremely aggressive, and is known from previous work, to go on to become the next queen if the original queen is not returned. When the original queen is returned after a day’s absence, she re-establishes herself as the queen and she usually manages to do so with little or no aggression. We hypothesize that R. marginata queens use dominance behaviour to suppress worker reproduction in the beginning, and that they use pheromones to regulate worker reproduction once they establish themselves and start laying eggs. If this hypothesis is correct, R. marginata would be an ideal model system to study the possible evolutionary transition from physical inhibition to chemical regulation of worker reproduction, and the transition from primitively eusocial to highly eusocial in general.