PEST MANAGEMENT Developing a Sterile Insect Release Program for Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae): Effective Overflooding Ratios and Release-Recapture Field Studies

In an effort to continue the development 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) overßooding ratio inside large Þeld cages containing Opuntia stricta Haworth (Haworth) host plants. Insects were allowed to mate and lay eggs, and all eggstickswere collected daily. Percent egg hatch and reduction inF1 fertile larvae were used to ascertain the effectiveness of each release combination. In addition, limited Þeld release-recapture experiments were conducted to examine the dispersal ability of untreated and treated cactus moth males. Results suggest that an overßooding ratio as low as 5:1 can effectively suppress C. cactorum in Þeld cages and that releasing both genders together is more effective than releasing males only. In open Þeld releases, the dispersal ability of C. cactorum was not signiÞcantly affected by treating the adults with gamma radiation.