The ecology of female receptivity in the territorial butterfly Hypolimnas bolina (L.) (Nymphalidae): implications for mate location by males

Abstract

Many male insects aggressively defend specific perching sites containing larval resources. There are three main explanations for how this behaviour could contribute to increased matings: perching males may aim to encounter (1) eclosing or freshly eclosed virgin females, (2) previously mated, ovipositing females, or (3) receptive females that visit these sites either specifically to mate or for other reasons. I evaluated these hypotheses by investigating the timing of post-eclosion female receptivity and the extent of polyandry within an Australian population of the butterfly Hypolimnas bolina (L.) (Lepidoptera: Nymphalidae). This species represents the group of butterflies in which males defend specific, geographically prominent, sites that overlap with the distribution of larval resources. Freshly emerged female H. bolina refrained from mating until their ovaries were close to maturation, resulting in a pre-mating period of 4–8 days. The presence of this substantial refractory period rules out the hypothesis that males defend pupation sites with the aim of mating with eclosing or freshly eclosed females. Secondly, almost 90% of females within the studied population carried only one spermatophore, a finding that mediates against the possibility that most perching males target (already mated) ovipositing females. The ‘rendezvous-site’ hypothesis is the most likely general explanation for territoriality in H. bolina; however, it remains unclear whether the distribution of larval hostplants per se has a primary influence on territory selection by males in this species.