EFFECT OF SEASONAL PLACEMENT OF COTESIA-MELANOSCELA (HYM, BRACONIDAE)ON ITS POTENTIAL FOR EFFECTIVE AUGMENTATIVE RELEASE AGAINST LYMANTRIA-DISPAR (LEP, LYMANTRIIDAE)

Cohorts of Cotesia melanoscela (Ratzeburg) (Hymenoptera: Braconidae) c ocoons were exposed in the held at three Maryland locations to attack by natural enemies for two week periods, then were held in an outdoor insectary until C. melanoscela adult or hyperparasitoid emergence. The timing of placement of the C. melanoscela cocoons in the field had a profound effect on the number of C. melanoscela that survived and emer ged as adults in synchrony with the field occurence of susceptible ear ly-instar Lymantria dispar (L.) larvae. The proportion of emerged adul ts available during susceptible host stages ranged from 1-92 %, depend ing on dates of release. November or December placements of C. melanos cela cocoons were most effective with 74-92 % emergence of adults duri ng peak periods of susceptible host stages. Spring placements were lea st effective. The causes of ineffective placement, which varied with l ocation and with date, were program (handling) loss, non-emergence, at tack by hyperparasitoids, predation, and C. melanoscela adult emergenc e at times when appropriate L. dispar life stages would not be present . We concluded that November/December releases avoided natural enemies and promoted appropriate diapause and post-diapause development that enhanced survival and synchrony of adult emergence with host stage sus ceptibility.