Host Selection Behaviour of the Parasitoid Leptopilina Cla Vipes , in Relation To Survival in Hosts
1990
Driessen, Gerard | Hemerik, Lia | Boonstra, Barrie
HOST SELECTION BEHAVIOUR OF THE PARASITOID LEPTOPILINA CLA VIPES , IN RELATION TO SURVIVAL IN HOSTS by GERARD DRIESSEN, LIA HEMERIK* and BARRIE BOONSTRA (University of Leiden, Department of Population Biology, P. O. Box 9516, 2300 RA Leiden, The Netherlands) ABSTRACT The probability of survival to adulthood of Leptopilina clavipes, a solitary en- doparasitoid of Drosophila larvae developing in fungi, was studied in 6 of its potential host species. Survival probabilities ranged from 0 % to 100%. Decisions concerning which hosts to parasitize directly affect offspring production. Host selection decisions of parasitoids with respect to 4 of the Drosophila species were studied in laboratory ex- periments. The results suggest that L. clavipes is unable to distinguish between D. phalerata and D. kuntzei. Larvae of D. busckii and D. immigrans are selected roughly in accordance with the survival probabilities for these species. With the exception of D. immigrans, oviposition behaviour of wild caught parasitoids towards these Drosophila was the same. KEY WORDS: Drosophila, parasitoids, survival, host species selection. INTRODUCTION In the Netherlands, Drosophila larvae are attacked by at least 13 species of parasitoids (VET & VAN ALPHEN, 1985, JANSSEN et al., 1988; DRIESSEN 2t al., 1990). Depending on the type of breeding substrate and the season, the risk of parasitism can sometimes reach 1007lo (JANSSEN et al., 1988; DRIESSEN & HEMERIK, 1991). However, a number of mechanisms lead to the emergence of adult Drosophila each generation. One of these is the ability to kill the parasitoid's egg before it can become harmful. Encapsulation of eggs is a wide-spread method of eliminating parasitism in Drosophila (CARTON et al., 1986), although other mechanisms are known (STREAMS, 1968). The ability to eliminate parasitism is often not uniformly effective, meaning that a particular host species will not survive parasitism by different
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