2005 Volume 40 Issue 3 Pages 387-390
A release test was conducted to suppress the winter cherry bug, Acanthocoris sordidus Thunberg, using a scelionid egg parasitoid, Gryon philippinense (Ashmead), in a greenhouse with grown green bell peppers at Kochi University, Japan, from June to September, 2003. The study site was divided into two areas (6 m×5.4 m), a release area and a control area. Three pairs of field-collected A. sordidus were released to each plant in both areas on June 15. Just after the first oviposition of A. sordidus was observed, G. philippinense females (1-d old) cultured in a laboratory were dispersed in the release area. Starting on June 16, releases were made in 5 batches of 50 mated females 5–7 d apart. In the control area, the hatchability of A. sordidus was 98.4% in a total of 8,375 eggs. In the release area, the parasitism rate of G. philippinense was 98.8% in a total of 7,725 eggs, and its emergence rate was 99.8%. The last release of the parasitoid was on July 8; however, the emergence of G. philippinense continued until mid-September. G. philippinense persisted in greenhouse conditions with the highest temperature being 49.0°C in August. The density of new-generation adults of A. sordidus was extremely low in the release area. This study showed that G. philippinense could be considered a useful biological control agent of A. sordidus.
