Frequent successful multiparasitism by five parasitoids attacking the scale insectNipponaclerda biwakoensis

Successful multiparasitism by five parasitoid wasps of the scale insectNipponaclerda biwakoensis was investigated at a reed bed in Lake Biwa. The wasps were gregarious endoparasitoids consuming the entire body of the host. The rate of successful multiparasitism for a parasitoid species was defined as the proportion of the number of individual hosts from which the species emergedwith other species to the total number of hosts from which the species emerged. The rates were high for each parasitoid species, ranging from 17 to 82%. Successful multiparasitism frequently involved two species with similar adult size, but rarely involved species with different adult size. For four of the five species, the number of wasps per host was significantly less when wasps emerged from a host with other species relative to when emerged alone. For the other one species, the number of wasps was less, but the difference was not significant. With only one species, female wasps were significantly smaller when they emerged from a host with other species relative to when emerged alone.