Interactions between the winter cherry bug <Emphasis Type="Italic">Acanthocoris sordidus</Emphasis> (Hemiptera: Coreidae) and its egg parasitic wasps

Detailed research on the relative strength of the influence of parasitoids on hosts has contributed to the development of biological control techniques. Gryon philippinense (Ashmead) is a major egg parasitoid of the winter cherry bug, Acanthocoris sordidus (Thunberg). However, available data are insufficient to determine which egg parasitoids have the strongest effect on mortality of A. sordidus or why G. philippinense is the major egg parasitoid of A. sordidus. In this study, G. philippinense attained a much higher level of parasitism on A. sordidus eggs compared to four other parasitoid species. Mortality induced by G. philippinense on A. sordidus egg clusters occurred in an all-or-none manner, whereas mortality caused by the four other parasitoids occurred in a random manner. Compared to Ooencyrtus spp., G. philippinense required a significantly shorter time to parasitize an A. sordidus egg and also parasitized significantly more A. sordidus eggs within 24 h. These findings demonstrate that a short handling time allows G. philippinense to be the most significant egg parasitoid of A. sordidus.