Field Experiments with Sterile Males for Eradication of the Boll Weevil123

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Abstract
From June 17 through August 26, 1964, 11 weekly releases of apholate-sterilized male boll weevils, Anthonomus grandis Boheman, were made in 9 cottonfields, (15.8 acres) that had been treated with insecticides the fall of 1963 to reduce the population of diapausing weevils. These weekly releases ranged from 3270 to 26,620 sterile weevils per acre (an average of 8200 per acre). Migrant weevils entering the release zone from other areas may have caused the program to achieve population suppression rather than eradication, though the release zone was surrounded by a 120-acre zone that had received the same fall treatment and was treated intensively with insecticides in 1964 and by another 115-acre buffer zone that was treated with insecticides in 1964. However, the apholate sterilized only an average 95.8% of the weevils and caused a substantial reduction in mating competitiveness. The release of the sterile males against the low-level population achieved by the 1963 fall applications reduced the number of oviposition-punctured squares compared with the number in the other 2 zones. Also the percentage of infertile eggs, the numbers of live immature and adult weevils per acre in fruit, the numbers of adults on plants and in hibernation sites, the numbers of overwintered adults, and the levels of infestation during the 2nd year or season after the releases were terminated were considerably lower in the release zone than in the zone treated intensively with insecticides.