Pupation site and emergence time influence the mating success of bagworm females,Oiketicus kirbyi

In commercial oil palm plantations in Costa Rica, we tested the hypotheses that pupation site and emergence time affect the mating success of protogynous female bagworms,Oiketicus kirbyi (Guilding) (Lepidoptera: Psychidae). Greater proportions of female than male pupae on upper leaves of oil palms and greater proportions of mated females in the upper rather than lower crown strata support the hypothesis that selection of pupation site by female larvae influences the mating success of adults. Increasing captures of males with increasing trap height further suggest that enhanced mating success of females in tree tops may be attributed either to most effective dissemination of sex pheromone on higher sites, or to males foraging predominantly in the upper strata of oil palms. As the majority of females pupated in the middle rather than upper crown of oil palms, selection of pupation site by females may be affected by additional as yet unknown factors. Emergence of females significntly preceded emergence of males. Increasing proportions of mated females throughout the emergence seasons probably resulted from an increased ‘availability’ of males. In tropical rainforests with local variations inO. kirbyi developmental time and stage, protogyny may represent an evolutionary strategy that furthers outbreeding.