121 



226. ; Simmons, L. A.; and Nilakhe, S. S. 1979. Laboratory studies of 

 sterility and competitiveness of boll weevils irradiated in an atmo- 

 sphere of nitrogen, carbon dioxide, or air. J. Econ. Entomol. 72: 687-691. 

 Almost all male Anthonomus grandls grandis Boheman treated with 7 krad of 

 gamma irradiation in air were dead within 14 days but over half of the 

 males irradiated in an atmosphere of nitrogen lived for at least 21 days. 

 Males were still 98-100% sterile when allowed to mate 3 and 7 days after 

 treatment with 7 krad in nitrogen; however, by the 10th day, sterility had 

 dropped to ca. 85%. Dissections on the 21st day posttreatment revealed that 

 many males had enlarged testes with sperm bundles, indicating that they had 

 recovered fertility. A dosage of 10 krad in nitrogen was required to main- 

 tain a level of at least 99% sterility; at this dosage level, survival, 

 sterility in both sexes, and male mating capability were the same as for 8 

 krad in air. In laboratory tests, sexual competitiveness of males exposed 

 to 10 krad in nitrogen (0.85) was significantly higher than that of males 

 exposed to 8 krad in air (0.51). These competitiveness values from the 

 laboratory studies were much higher than the published figures for weevil 

 competitiveness in the field (0.17-0.36). This lack of agreement indicates 

 that not all of the significant factors associated with male competitiveness 

 are measured by the usual laboratory tests. 



• 



227. ; Simmons, L. A.; Nilakhe, S. S.; Villavaso, E. J.; McKibben, G. H. ; 

 and Sikorowski, P. 1978. Pheromone production and sterility in boll 

 weevils: Effect of acute and fractionated gamma irradiation. J. Econ. 

 Entomol. 71: 591-595. 

 Each of 3 methods of irradiating male Anthonomus grandis Boheman resulted in a 

 unique pattern cf pheromone production over a 12-day period of observation. 

 Peak pheromone production occurred 4-6 days after treatment in males given a 

 single large dose of gamma irradiation (acute irradiation) at the age of 4 



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