Effect of irradiation on death-feigning behavior in the male sweetpotato weevil cylas formicarius (Coleoptera: Blentidae)

Abstract

The sterile insect technique (SIT) is widely used to suppress or eradicate target insect pest populations. The effectiveness of SIT depends on the ability of the released sterile males to mate with and inseminate wild females. Irradiation is effective for sterilizing mass-reared insects, and the negative impacts of this procedure are not limited to reproductive cell damage. In this study, we evaluated the death-feigning that is considered as an antipredator behavior of male Cylas formicarius (Summers) (Coleoptera: Blentidae) irradiated with 200 Gy, which is the dose used in the SIT program in Okinawa Prefecture. Irradiated male insects were observed in the laboratory for 10 d after irradiation. On d 0, fewer irradiated males feigned death than nonirradiated males. The number of irradiated and nonirradiated males who feigned death and the duration of their death-feigning were about the same from 2 d after irradiation. On the basis of our results, we discuss the optimal release time of irradiated male C. formicarius.