Variation in diapause and sex ratio in the parasitoidAsobara tabida

Asobara tabida Nees (Hymenoptera: Braconidae) is a widespread parasitoid, attacking larvae ofDrosophila (Diptera: Drosophilidae) species in fermenting substrates. In this species, geographic variation is found in the percentage of parasitoids entering diapause and in the sex ratio of emerging parasitoids. Percentage diapause appears to be influenced by host species (more parasitoids enter diapause inD. melanogaster Meigen than inD. subobscura Collin) and temperature. It is not correlated with any of the abiotic factors investigated, but is correlated with survival probability inD. melanogaster larvae and with the time of year in which the experiment was conducted (even though none of the parasitoids experienced natural day light). Sex ratio was only found to correlate with percentage diapause, suggesting that males enter diapause more frequently than females. It is concluded thatA. tabida uses diapause to survive both unfavourable abiotic and biotic circumstances.