J. Brodeur et al., EFFECTS OF PIERIS HOST SPECIES ON LIFE-HISTORY PARAMETERS IN A SOLITARY SPECIALIST AND GREGARIOUS GENERALIST PARASITOID (COTESIA SPECIES), Entomologia experimentalis et applicata, 86(2), 1998, pp. 145-152
Host specificity and host selection by insect parasitoids are hypothes
ized to be correlated with suitability of the hosts for parasitoid dev
elopment. The present study investigates the correlation between host
suitability and earlier studied host-finding behaviour of two closely
related braconid larval parasitoid species, the generalist Cotesia glo
merata (L.) and the specialist C. rubecula (Marshall) (Hymenoptera: Br
aconidae). We compared the capability of both parasitoid species to pa
rasitize and develop in three Pieris host species, i.e. P. brassicae (
L.), P. rapae (L.) and P. napi (L.) (Lepidoptera: Pieridae). In labora
tory experiments, we measured the effect of host species on fitness pa
rameters such as survival, development, sex ratio and size of parasito
id progeny. The results show that C. glomerata is capable of developin
g in the three host species, with significant differences in parasitoi
d survival, clutch size and adult weight among Pieris species. The hos
t range for development was more restricted for C. rubecula. Although
C. rubecula is physiologically able to develop in P. brassicae larvae,
parasitoid fitness is negatively affected by this host species, compa
red to its most regular host, P. rapae. A comparison of the present da
ta on host suitability with earlier studies on host-searching behaviou
r suggests that the host-foraging behaviour of both parasitoid species
not only leads to selection of the most suitable host species for par
asitoid development, but also plays a significant role in shaping para
sitoid host range.