PATTERNS OF HYPERPARASITISM OF COTESIA-MELANOSCELA (HYMENOPTERA, BRACONIDAE) IN SOUTHERN ONTARIO

Patterns of hyperparasitism of cocoons of Cotesia melanoscela in southern Ontario were studied by periodic sampling of naturally occurring cocoons found under burlap bands and by deploying laboratory-produced sentinel cocoons on bark disks. At least six species of hyperparasitoids were recovered. The most common species of hyperparasitoids showed definite associations with sampling method and with red or white oak trees. Hyperparasitism of C. melanoscela began in early June and persisted throughout the summer. Peak activity of hyperparasitoids was in late June and early July and was coincident with the maximum number of available natural C. melanoscela cocoons in diapause. The probability of C. melanoscela survival during any single sampling interval declined steadily over the sampling period (14 June-3 August 1989). During this sampling period, 95.9% of the available C. melanoscela cocoons were killed by hyperparasitoids. This estimate of hyperparasitism is a minimum rate for Ontario; cocoons not attacked by the end of our sampling period were in diapause and thus were vulnerable to hyperparasitism for up to 10 mo after sampling ended.