Historical Perspective

Abstract

Male butterflies move over a large area in search of receptive females, infrequently returning to the same area, or patrol within a small area, frequently returning to the same locality. Factors affecting mate-locating behaviour have been mentioned traditionally in the abiotic environment, such as ambient temperature, as well as the biotic environment, such as body temperatures, lek assembly, and territorial perching. Visual cues can be used in the detection and discrimination of conspecific individuals by both sexes, because of their diurnal activities, although some species detect females by scent alone. Various courtship displays have been described in ethology. After adequate courtship behaviour by males, virgin females of most species will accept copulation. Until 30 years ago, it was believed that females in the majority of species mate only once, but that males have the capacity to mate more than once. A plug secreted by males of some species during copulation seemed to prevent further mating of females, supporting such female monogamy. Mate refusal postures of mated females when encountered by males also suggested maintaining female monogamy. Consequently, virgin females are receptive, showing little choice to mate, and mated females are faithful. However, counting the number of spermatophores in the bursa copulatrix of females has indicated that females of most species regularly mate more than once, because a single spermatophore is transferred from the male during a single copulation. Further matings occur after sperm reserves or nutrients are depleted, suggesting that females are not continuously available to mate. Although the sex ratio is unity, for most of the time there are more males than receptive females, and in such circumstances males are in competition to gain access to scarce receptive females. Therefore, female mate choice, particularly in mated females, would be favoured.