Conditional mating tactics in the queen of the inquiline ant Vollenhovia nipponica

Abstract

Alternative female reproductive strategies are more abundant in ants than other animals. Most cases involve morphological polymorphism in the queen which depends on the colony founding strategies. In the present study, we revealed the conditional mating tactics of the queen of the inquiline ant Vollenhovia nipponica. The queens had two mating tactics, mating in nests and by nuptial flight. Field collections of parasitized colonies in autumn and springyielded colonies that usually included virgin alate queens and dealate queens which had already mated with males in nests. In autumn when the new queens eclosed, the proportion of dealates to all queens was largely stable (average: 0.27), suggesting that some of new queens did not mate in the nests but adopted mating by nuptial flight after hibernation. However, the measurement of head width in alate and dealate queens showed that there was little difference in body size between them. To test whether alate queens change their mating tactics according to the conditions, we attempted mating induction experiments. In the laboratory, all dealate queens were removed from seven experiment colonies. As a result, all alate queens immediately started to mate with males in nests, and no alates remained in any of the colonies after two weeks. It is suggested that alate queens change their mating tactics according to the mating condition of the other queens in the nest.