Alternative Female Choice Tactics in the ScorpionflyHylobittacus apicalis(Mecoptera) and Their Implications

Abstract

Females of the scorpionfly Hylobittacus apicalis choose mates on the basis of material benefits (nuptial arthropod prey size) and probably on the basis of genetic benefits males deliver at mating. Females feed on the male's prey throughout copulation. They prefer males with large prey as mates and often refuse males who present small prey. That females may value male genetic quality is suggested by differences in ability of males to obtain large prey, which if inherited would influence offspring fitness, and by females often terminating mating with males with small prey before they transfer any sperm or a complete ejaculate. Females hunt only when males with prey are not available because hunting exposes individuals to predators. Female Hylobittacus apicalis exhibit alternative mate choice tactics, which are condition-dependent in expression and probably comprise a conditional strategy. Body size, recent feeding history, and male availability determine how discriminating an individual female actually is, and these conditions may determine the value of material and genetic benefits in mate choice decisions. The results suggest that female choice controls male behavior. When females become choosy, males are forced to obtain rare large prey despite the increased risks to males associated with this behavior. The implications of the findings on H. apicalis are discussed in relation to condition dependent female choice patterns in other species and the evolutionary maintenance of female choice.