Use of a factitious host and supplemented adult diet to rear and induce oogenesis in Catolaccus grandis (Hymenoptera : Pteromalidae)

Augmentation and release of the ectoparasitoid Catolaccus grandis (Burks) against the boll weevil, Anthonomus grandis grandis Boheman, has relied on the production of boll weevils for the past 15 yr. Eliminating this dependence on a host that is expensive to rear could make this technology commercially viable. Seven species of insects that are more easily reared than the boll weevil were tested as factitious hosts of C. grandis . Four species were lepidopterans— Galleria mellonella (L.), Helicoverpa zea (Boddie), Heliothis virescens (F.), and Chilo plejadellus Zincken. Only H. zea and H. virescens stimulated oviposition by C. grandis ; nevertheless this parasitoid did not complete development in any of these lepidopterans. The other 3 species were coleopterans— Chalcodermus aeneus Boheman, Anthonomus eugenii Cano, and Callosobruchus maculatus (F.). Females of C. grandis oviposited and parasitoids completed development in all coleopteran species. C. grandis females reared on C. maculatus oviposited significantly more eggs per day than those reared on A. eugenii or C. aeneus . Chemical analyses showed that the concentrations of proline, histidine, glutamine, and tyrosine in C. maculatus and A. eugenii hemolymph most closely resembled those of A. g. grandis hemolymph. The effectiveness of the factitious hosts to stimulate oogenesis was indirectly tested by comparing oviposition rates of females exposed to the factitious hosts to those of naive females. Even though A. eugenii and C. maculatus stimulated oogenesis (conditioning) in C. grandis females after 3 d of exposure, the degree of stimulation was significantly lower than that induced by exposure to A. g. grandis prepupae. The results indicate that C. maculatus is a promising factitious host to rear and condition C. grandis females.