Boletín de la AeE

In the superfamily Chalcidoidea 1 1 of the 17 families display hyperparasitism. In the Eupelmidae, the progeny of Eupelnnis vnilleíi and E. Orientalis, can be either primaiy or secondary parasitoids.

When the two species act as primary ectoparasitoids on bean weevil larvae, there is a strong coiTelation between the sex of the progeny and host size: male eggs are preferentially laid on lighter host larve and female eggs on heavier ones.

Is this manipulation of the ratio always maintained when these Eupelmid parasiotids act as secondary parasitoids?

When E. vnilleti developed as a hyperparasitoid on the last larvas stages of a parasitoid competítor Dinartmts basaüs (i.e. the heavier stages L5 and pupae), the sex ratio of offspring was very cióse to that observed when E. vuilleU acted as primary parasitoids (70, 40% of females in the total progeny as primary parasitoids against 64,40% as secondary parasitoids).

When E. orienlalis developed as a hyperparasitoid on the last larval stages of her own species (i.e. L5, prepupae, males and females pupae), although offspring of signiñcantly different weights were produced the coiTelation disappeared between the sex ratio of the progeny and the size of hosts (65,40% of females in the total progeny as primaty parasiotids against 14,60% as secondary parasitoids).

It seemed that the Eupelmidae were able to manipúlate the sex of their progeny when they acted as hyperparasitoids with respect to the characteristics of the primary parasitoids. In the presence of competitors of a distant family there was interspecific recognition and, the manipulation of sex ratios was in favour of females to maintain the population. In the presence of their own species, the relation between the sex and size of the host was not maintained and males were more abundant.