Forest and laboratory evaluations of hybridizedApanteles melanoscelus [Hym.: Braconidae], a parasitoid ofPorthetria dispar [Lep.: Lymantriidae]

Hybrids ofApanteles melanoscelus (Ratzeburg) were produced from colonies originating from France, Yugoslavia, and Connecticut. All strains, as well as freshly collected “wild” Connecticut parasitoids of the same species were evaluated in the laboratory for developmental rate, host attack rate, and sex ratios. Development was significantly slower in all the laboratory strains compared to the progeny of forest collected Connecticut females. Progeny production was greater (almost 2X) for the “wild” females and the French-Yugoslavian-Connecticut hybrid than for the laboratory Connecticut strain. The proportion of females collected from the “wild” (Connecticut) strain was higher than that observed in any laboratory strain. A field test was conducted using the triple hybrid in 3 release plots with ca. 6000A. melanoscelus cocoons released per plot in central Connecticut, U.S.A. Weekly collections of gypsy moth larvae showed that the % parasitism was significantly higher in release plots than in the 3 check plots. These results suggest the value of inundative releases ofA. melanoscelus for reduction of sparse gypsy moth populations, but they did not show that hybridization of these strains produced a more effective parasitoid under forest conditions.