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Title: POTENTIAL USE OF IN VITRO-REARED CATOLACCUS GRANDIS (HYMENOPTERA: PTEROMALIDAE) FOR BIOLOGICAL CONTROL OF THE BOLL WEEVIL (COLEOPTERA: CURCULIONIDAE)

Author
item MORALES-RAMOS, JUAN - TX AGRI EXPER STATION
item Rojas, Maria - Guadalupe
item Coleman, Randy
item King Jr, Edgar

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The introduced natural enemy of the boll weevil, Catolaccus grandis, has been tested with success against infestations of this pest in south Texas during the past 4 years. However, the high cost of mass propagating this beneficial wasp limits its commercial application. One important step in making the use of this wasp commercially available has been the development tof an artificial diet for C. grandis. The purpose of this research is to determine if there is a decrease in the quality of C. grandis after being reared for 5 and 10 consecutive generations in artificial. A second objective was to compare the searching efficiency of wasps reared in artificial diet to those reared on their natural host. The results show that after 5 consecutive generations of diet rearing no significant changes occur on the quality of the wasps. However, a slight decrease in fecundity occurs after being reared on diet for 10 consecutive generations. No difference was observed on field performance of wasps reared on artificial diet and those reared on their natural host. The study concludes that the use of an artificial diet to mass propagate and release C. grandis is a viable strategy of biological control of the boll weevil.

Technical Abstract: The biological characteristics of the ectoparasitoid Catolaccus grandis (Burks) were evaluated after 1, 2, 5, and 10 generations of in vitro- rearing and compared to parasitoids reared on boll weevil, Anthonomus 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 reproduction 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, Texas. 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.