ORTHOSIA HIBISCI GUENÉE (LEPIDOPTERA: NOCTUIDAE): INDIGENOUS PARASITOIDS AND THE IMPACT OF EARINUS LIMITARUS (SAY) (HYMENOPTERA: ICHNEUMONIDAE) ON ITS HOST FEEDING ACTIVITY

Abstract

AbstractA 3-year survey of apple and cherry orchards in the interior of British Columbia revealed that speckled green fruitworm, Orthosia hibisci, is the dominant fruitworm species in the south of the Okanagan Valley. Larvae of speckled green fruitworm collected from orchards that used no or minimal insecticides experienced 22.5–29.0% parasitism in 1988–1990. Earinus limitarus was responsible for 98.9% of the parasitism in the 3 years. Parasitoids of minor significance included a Meteorus sp. (Hymenoptera: Braconidae) and Compsilura concinnata (Mg.) (Diptera: Tachinidae). Data from laboratory trials indicated that feeding by O. hibisci in the fifth and sixth instars was significantly (P < 0.05) reduced when larvae were parasitized by E. limitarus. Orthosia hibisci in the second through sixth instars in sleeve cages damaged developing apples in the field. Earinus limitarus appears able to reduce O. hibisci numbers for the following year as well as immediate host feeding damage in at least the last two instars.