Suitability of Prepupae and Pupae of the Gypsy Moth (Lepidoptera: Lymantriidae) as Hosts of Coccygomimus disparis (Hymenoptera: Ichneumonidae)

Females of Coccygomimus disparis (Viereck) were exposed to laboratoryreared prepupae and pupae (1–9 d old) of the gypsy moth, Lymantria dispar (L.), in a choice test to determine the optimal host age for parasitism. The frequency of visits by parasites and successful parasitism in a 2-h exposure period were high for all age classes of pupae but markedly lower for prepupae. Incidence of parasitism appeared to be higher on male hosts than female hosts, but the sex ratios were similarly skewed toward females in progeny emerging from hosts of both sexes. Development of more than one parasite per host was very rare. Host mortality caused by dehydration was higher in prepupae than in pupae but did not appear to be caused by parasite activity, nor did mortality from disease. Host mortality from unknown causes was much higher in hosts that were known to have been visited than in those that were not, suggesting that some of this mortality should be attributed to parasite activity.