GEOGRAPHICAL VARIATION IN ENCAPSULATION ABILITY OF DROSOPHILA-MELANOGASTER LARVAE AND EVIDENCE FOR PARASITOID-SPECIFIC COMPONENTS

The ability of Drosophila melanogaster larvae in Europe to encapsulate the eggs of their most important parasitoids, Asobara tabida and Lept opilina boulardi, shows a large amount of geographical variation. Inte restingly, encapsulation ability against A. tabida is not correlated w ith encapsulation ability against L. boulardi. This indicates that the encapsulation system of D. melanogaster larvae has parasitoid-specifi c components. The variation in encapsulation ability can only partly b e explained by the incidence of parasitism on the larvae. This means t hat factors other than the two parasitoid species must be selection pr essures on the encapsulation ability of D. melanogaster larvae.