Suitability of the maize weevil and angoumois grain moth as hosts for the parasitoids Anisopteromalus calandrae and Pteromalus cerealellae

Abstract

AbstractTwo parasitoids, Pteromalus cerealellae (Ashmead) and Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), were compared for their ability to parasitize two important internally‐developing insect pests of stored maize (Zea mays L.). Parasitism by P. cerealellae was greater on Angoumois grain moth, Sitotroga cerealella (Olivier), than on maize weevil, Sitophilus zeamais Motschulsky, in no‐choice experiments. Anisopteromalus calandrae parasitized more maize weevils than did P. cerealellae. The former parasitoid parasitized only a few Angoumois grain moths successfully in maize, but parasitized many in wheat if the hosts were younger than 3 weeks old. Thus, both host age and type of grain affect suitability for parasitism. The effects of parental host (species on which the female developed) and experimental host (species exposed to parasitism) on parasitism rate of P. cerealellae were tested in a host‐switching experiment. Parasitism by parasitoids reared on maize weevils was 23% lower than that of parasitoids reared on Angoumois grain moth. This effect was independent of which host the filial generation of parasitoids was tested on. However, the experimental host species had a much greater effect on parasitoid fecundity than the parental host species. Female progeny had smaller body sizes when emerging from maize weevil than from Angoumois grain moth, which may explain the parental host effect on fecundity. There was also a slight intergenerational effect of host species on parasitoid body size.