Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2005
Publication Date: 8/1/2005
Citation: Hight, S.D., Carpenter, J.E., Bloem, S., Bloem, K.A. 2005. Developing a sterile insect release program for Cactoblastis cactorum (Berg) (Lepidoptera:Pyralidae): Effective overflooding ratios and release-recapture field studies. Environmental Entomology. 34(4):850-856. Interpretive Summary: The South American cactus moth was found in North America for the first time in 1989. The insect has spread from the Florida Keys and now occurs along the coastal areas of southeastern United States from the tip of the Florida panhandle to South Carolina. Spread of the moth into the southwestern United States and Mexico, areas that are rich in cactus diversity, is of great concern to environmentalists and agriculturalists. Scientists with USDA Center for Medical, Agricultural and Veterinary Entomology in Tallahassee, FL and Crop Protection and Management Research Unit in Tifton, GA are looking into ways of controlling this insect and limiting its westward spread. The Sterile Insect Technique (SIT) is one method that may stop the moth and perhaps push back its leading edge. In a SIT program, sterilized cactus moths would be released in large numbers and matings between sterile and wild moths would result in fewer and less-fit offspring. Based on a field-cage study, releasing only five times more sterile insects than fertile insects was enough to substantially lower the reproduction of fertile insects. Also, releasing both sterilized males and females was more effective than releasing only sterilized males.
Technical Abstract: In order to develop of a sterile insect release program against the invasive cactus moth, Cactoblastis cactorum (Berg.), we released partially sterile males alone or in combination with fully sterile females at a 5:1 or 10:1 (treated:fertile) overflooding ratio inside large field-cages containing Opuntia stricta Haworth (Haworth) host plants. Insects were allowed to mate and lay eggs and all eggsticks were collected daily. Percent egg hatch and reduction in F1 fertile larvae was used to ascertain the effectiveness of each release combination. In addition, limited field release-recapture experiments were conducted to examine the dispersal ability of untreated and treated cactus moth males. Results suggest that an overflooding ratio as low as 5:1 can effectively suppress C. cactorum in field-cages, and that releasing both genders together is more effective than releasing males only. Finally, the dispersal ability of C. cactorum is not significantly affected by treating the adults with gamma radiation.