Dominance relationship in the establishment of reproductive division of labour in a primitively eusocial wasp (Ropalidia marginata)

Abstract

In mature post-emergence colonies of the tropical primitively eusocial polistine wasp Ropalidia marginata, the queen is not a behaviourally dominant individual. Nevertheless, she completely suppresses reproduction by the workers and becomes the sole egg-layer in the colony. Mechanisms by which a female is able to establish her exclusive reproductive status in the colony can be investigated by examining dominance-submission relationships and hierarchy formation at particular stages of the colony cycle when reproductive competition is behaviourally manifest. Observations on the behaviour of R. marginata females (1) during early stages of colony-founding, (2) when potential queens challenge the existing queen, and (3) immediately after queen replacement show that these wasps use highly aggressive dominance interactions to establish their reproductive status. Both the frequency and the intensity of dominance behaviours are significantly higher at these stages than those observed at phases of the colony when there is no apparent reproductive strife. Once her position as the only egg-layer of the colony has been established, the levels of dominance interactions initiated by the queen decrease and the nature of these interactions also becomes comparatively milder. Thus, the mechanisms by which a queen establishes her social status in her colony and those by which she continues to suppress reproduction of her nestmates in the absence of overt physical dominance may be quite different.