Exploratory Studies on Gamma Radiation for the Sterilization of the Boll Weevil

The effect of gamma radiation on boll weevil ( Anthonomus grandis Boheman) adults, pupae, and eggs was determined following exposure to cobalt60 Longevity and egg-laying capacity of reproducing weevils were drastically reduced at doses of 5,000 roentgens (r) or higher, whereas egg hatch was greatly reduced at doses as low as 2,500 r. Exposure of virgin males to 10,000 r resulted in transient sterility whereas 15,000 r produced permanent sterility. However, these doses resulted in very rapid mortality of both sexes. A ratio of 3.8:1:1 of sterilized males: normal males: normal females did not affect egg laying or hatch. There appeared to be little, if any, effect of adult boll weevil age on susceptibility to the lethal effects of gamma rays. Emergence of adults from prepupae, young, and old pupae exposed to 10,000 r was eliminated, greatly reduced, and unaffected, respectively. However, the lethal effects carried over because all of the adults died within 2 weeks. Exposure of eggs to 600 r did not affect hatch or subsequent development whereas 2,400 drastically reduced hatch and prevented subsequent development.