Effects of delayed mating on reproductive output of female oriental beetle Anomala orientalis (Coleoptera: Scarabaeidae)

Abstract

Abstract1 Although management of the oriental beetle Anomala orientalis (Waterhouse) by mating disruption shows promise across a range of agricultural systems, relatively little is known about aspects of the reproductive biology of this species relevant to its management. We studied the effects of delayed mating on several aspects of the oviposition behaviour and biology of the oriental beetle using females mated in the laboratory at 4–13 days posteclosion.2 Females exhibited a gradual decline in fecundity with increased age at mating that was largely a function of a decline in duration of the oviposition period, as well as lower female fertility: females mated at 11 days were less likely to lay any fertile eggs. However, egg fertility did not vary with female age at mating.3 Because mating delay did not affect longevity, females mated at older ages experienced decreased oviposition periods; however, females laid more eggs per day with increased age at mating, which partially offset shorter oviposition periods.4 A mating delay of ≥ 6 days relative to females mated within the first day of reaching sexual maturity resulted in an approximately 35–50% lower mean fecundity.5 These results suggest that, for mating disruption to be a successful management tool for the oriental beetle, mating must be prevented rather than delayed. We compare the findings of the present study with the published research on delayed mating in moths and discuss the importance of these results in relation to management of the oriental beetle using female sex pheromones.