Limited mobility of target pests crucially lowers controllability when sterile insect releases are spatiotemporally biased

• Published in: Journal of theoretical biology Vol. 421; pp. 93 - 100
• Main Authors: Ikegawa, Yusuke, Himuro, Chihiro
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 21.05.2017
• Subjects: Animals; Directed dispersal; Euscepes postfasciatus; Fertility; Genetic pest control; Insect Control - methods; Insect Control - statistics & numerical data; Insecta - genetics; Ipomoea batatas - parasitology; Japan; Models, Biological; Models, Theoretical; Pest Control, Biological - methods; Reproduction; Spatio-Temporal Analysis; Sterile insect technique; Two-patch population model; Weevils; Directed dispersal; Genetic pest control; Two-patch population model; Sterile insect technique; Euscepes postfasciatus
• ISSN: 0022-5193; 1095-8541
• DOI: 10.1016/j.jtbi.2017.03.026

•Sterile insect technique (SIT) is applied to control of a pest with limited mobility.•Effect of spatiotemporal evenness of sterile insect releases on SIT is examined.•Spatiotemporally biased releases crucially inhibit regional pest eradication.•The negative effect of biased releases results from low mobility of the insects. The sterile insect technique (SIT) is a genetic pest control method wherein mass-reared sterile insects are periodically released into the wild, thereby impeding the successful reproduction of fertile pests. In Okinawa Prefecture, Japan, the SIT has been implemented to eradicate the West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire), which is a flightless agricultural pest of sweet potatoes. It is known that E. postfasciatus is much less mobile than other insects to which the SIT has been applied. However, previous theoretical studies have rarely examined effects of low mobility of target pests and variation in the spatiotemporal evenness of sterile insect releases. To theoretically examine the effects of spatiotemporal evenness on the regional eradication of less mobile pests, we constructed a simple two-patch population model comprised of a pest and sterile insect moving between two habitats, and numerically simulated different release strategies (varying the number of released sterile insects and release intervals). We found that spatially biased releases allowed the pest to spatially escape from the sterile insect, and thus intensively lowered its controllability. However, we showed that the temporally counterbalancing spatially biased releases by swapping the number of released insects in the two habitats at every release (called temporal balancing) could greatly mitigate this negative effect and promote the controllability. We also showed that the negative effect of spatiotemporally biased releases was a result of the limited mobility of the target insect. Although directed dispersal of the insects in response to habitats of differing quality could lower the controllability in the more productive habitat, the temporal balancing could promote and eventually maximize the controllability as released insects increased.