Ar. Kraaijeveld et Jjm. Vanalphen, VARIATION IN DIAPAUSE AND SEX-RATIO IN THE PARASITOID ASOBARA-TABIDA, Entomologia experimentalis et applicata, 74(3), 1995, pp. 259-265
Asobara tabida Nees (Hymenoptera: Braconidae) is a widespread parasito
id, attacking larvae of Drosophila (Diptera: Drosophilidae) species in
fermenting substrates. In this species, geographic variation is found
in the percentage of parasitoids entering diapause and in the sex rat
io of emerging parasitoids. Percentage diapause appears to be influenc
ed by host species (more parasitoids enter diapause in D. melanogaster
Meigen than in D. subobscura Collin) and temperature. It is not corre
lated with any of the abiotic factors investigated, but is correlated
with survival probability in D. 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 dia
pause more frequently than females. It is concluded that A. tabida use
s diapause to survive both unfavourable abiotic and biotic circumstanc
es.