The eradication projects and preventative control of quarantine pests in Okinawa, Japan

Of the several exotic insect species in Japan, five quarantine plant pest taxa: the oriental fruit fly, Bactrocera dorsalis complex, the melon fly, Zeugodacus cucurbitae, the solanaceous fruit fly, Bactrocera latifrons, the sweet potato weevil, Cylas formicarius, and the West Indian sweet potato weevil, Euscepes postfasciatus, have been targeted in eradication programs using the male annihilation technique (MAT) and/or the sterile insect technique (SIT). Although all targeted fruit flies have successfully been eradicated, the incidences of re-invasion by Bactrocera dorsalis complex have been increasing in recent years, indicating the necessity for reinforcement and improvement of countermeasures for fruit fly re-invasion and/or recolonization. The program targeted at C. formicarius achieved the goal of complete eradication in Kume Island. The program for E. postfasciatus has yet to achieve eradication, even though it was initiated at the same time as that for C. formicarius. Major technical improvements are required for successful eradication of E. postfasciatus

First case of successful eradication of the sweet potato weevil, Cylas formicarius (Fabricius), using the sterile insect technique.

This paper presents the first case of the successful eradication of a Coleoptera pest species over a wide area using a combination of male annihilation technique (MAT) and sterile insect technique (SIT) application. The sweet potato weevil, Cylas formicarius, is one of the most destructive and widely distributed pests of sweet potato, Ipomoea batatas. A project to eradicate it was launched in 1994 on Kume Island, Okinawa Prefecture, Japan. The MAT application was first used from November 1994 to January 1999 to reduce the density of wild populations. The distribution and densities of weevils were assessed by trapping them and surveying infestation rates in wild hosts and sweet potatoes in the field. The C. formicarius populations were suppressed by approximately 90% and plant infestations were reduced from 9.5% to less than 0.1% by using the MAT. Then, hundreds of thousands to millions of sterile weevils were released each week (ca. 460 million in total from 1999 to 2012). As a result, based on an analysis of 12748 stems and 48749 tubers, no weevil infections were detected in the stems or tubers of sweet potato since 1997. Since 2009, almost no wild weevils were captured in traps, and in wild host and sweet potato surveys no weevils have been found in any of the 580 locations and 8833 samples since October 2011. As of 28 December, 2012, C. formicarius is considered to have been eradicated from Kume Island. This paper describes the process of eradicating C. formicarius using SIT application integrated with MAT application for the first time and discusses some of the main challenges associated with the weevil eradication campaignl