Developing a Sterile Insect Release Program for<i>Cactoblastis cactorum</i>(Berg) (Lepidoptera: Pyralidae): Effective Overflooding Ratios and Release-Recapture Field Studies

Abstract

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) 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 were 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. In open field releases, the dispersal ability of C. cactorum was not significantly affected by treating the adults with gamma radiation.