Effect of long-term mass-rearing on mating performance in the West Indian sweet potato weevil, Euscepes postfasciatus

Abstract

A lot of sterile males need to be released continuously in the target area in the sterile insect technique (SIT). Therefore, mass-rearing of the target pest insects is indispensable for SIT programs. The West Indian sweet potato weevil, Euscepes postfasciatus, has been maintained for over 44 generations (~ 8 years) for its eradication program in the Okinawa Prefectural Plant Protection Center (Naha, Okinawa, Japan). The selective pressures under mass-rearing conditions are likely to be very different from those of wild ones. The specific selective pressures over many generations under mass-rearing conditions would adversely affect the reproductive capacity of mass-reared insects. Therefore, evaluation of the mating performance of mass-reared males compared with that of wild ones is indispensable in SIT eradication programs. Although we compared mating performance with respect to four reproductive characteristics (duration of mating behavior, mating success, mating competitiveness ability and number of transferred sperm in female spermatheca during copulation) between mass-reared and wild males in E. postfasciatus, there was no evidence that the mass-reared males were inferior to the wild males in terms of mating performance. Thus, we considered that the mass-rearing procedure for at least 44 generations did not adversely influence the male mating activity in E. postfasciatus.