DISCRIMINATION BETWEEN PARASITIZED AND NONPARASITIZED HOSTS BY THE GYPSY MOTH LARVAL PARASITOID,APANTELES MELANOSCELUS(HYMENOPTERA: BRACONIDAE)

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Abstract
Observations of behavior and dissections of hosts were carried out to investigate the ability ofApanteles melanoscelusRatzeburg (Hymenoptera: Braconidae) to distinguish between parasitized and nonparasitized gypsy moth larvae,Porthetria dispar(L.) (Lepidoptera: Lymantriidae). Fewer host examinations occurred and fewer eggs were laid in hosts which had been parasitized 0–9 days previously than in those which had never been parasitized. However, superparasitism occurred readily especially when few unparasitized hosts were available. By dissecting hosts which were parasitized more than once it was possible to investigate competition between supernumerary parasitoids. First instars are eliminated by some mechanism (possibly active combat), and older parasitoids eliminate younger ones.