Potential use of in vitro-reared Catolaccus grandis (Hymenoptera: Pteromalidae) for biological control of the boll weevil (Coleoptera: Curculionidae)

The biological characteristics of the ectoparasitoid Catolaccus grandis (Burks) were evaluated after 1, 2, 5, and 10 generations of in vitro-rearing and compared with parasitoids reared on boll weevil, Anthonoms grandis grandis Boheman, larvae. Pupal weight of females was not significantly affected after 10 generations of in vitro-reared wasps. Fecundity of C. grandis was not significantly reduced after 5 generations of in vitro-rearing. However, the in vitro F10 showed a significant reduction in fecundity. Females reared on boll weevils had a higher pupal weight and fecundity than females reared in vitro, but in vitro-reared females exhibited significantly higher survival during the period of most intensive reproductive activity. The movement, searching capacity, and survival under field conditions of in vitro and in vivo-reared C. grandis were compared in Ricardo and Lyford, TX. Dispersal ability and searching capacity was not significantly different within a 30-m radius for parasitoid females reared by either method. However, a significantly higher proportion of stations with parasitism was recorded from in vivo-reared C. grandis. at a 60-m radius from the release point. Nevertheless, no significant difference in boll weevil mortality induced by parasitism was recorded between the 2 methods. This shows that the use of artificial diets is a promising method for mass propagating C. grandis.