Influence of Radiation Dose on the Level of F1 Sterility in the Cactus Moth, Cactoblastis cactorum (Lepidoptera: Pyralidae)

Colothdian D. Tate, James E. Carpenter, Stephanie Bloem


We examined inherited sterility effects on the F1 and F2 generations of the cactus moth, Cactoblastis cactorum (Berg) after gamma sterilization. Our objectives were to identify the dose of gamma radiation that would fully sterilize F1-generation moths and result in no viable offspring when F1 males were inbred- or out-crossed to fertile females, and that would allow maximum production of F1 sterile C. cactorum adults by irradiated males. Newly emerged adults of C. cactorum were exposed to increasing doses of gamma radiation and inbred or out-crossed to fertile counterparts. Inherited effects resulting from irradiation of males and females were expressed in the F1 generation as reduced egg hatch, increased developmental time for the F1 egg, and increased F1 larval to adult mortality. These effects were most pronounced when parental adults were irradiated at 200 Gy. Survival of F1-generation offspring originating from irradiated male × fertile female crosses was greatest at 200 Gy. In addition, inbred- and out-crosses of surviving F1 adults, with 1 parent irradiated at 200 Gy, resulted in no F2 adults. Maximum production of sterile F1 adults at 200 Gy suggests this dose is the most appropriate dose for implementing the sterile insect technique (SIT)-F1 sterility for control of C. cactorum in North America and for testing host suitability and potential geographical range in the field.

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