Evaluation of a new method for sterilizing boll weevils (Coleoptera: Curculionidae) by dipping in a diflubenzuron suspension followed by irradiation

Boll weevils, Anthonomus grandis grandis Boheman, were sterilized by dipping in an aqueous suspension containing 0.4% (AI) diflubenzuron and antibiotics (0.03% kanamycin, 0.015% penicillin, and 0.015% chloramphenicol) for 10 min followed by 10 krad of irradiation. Overall, mortality was less than or equal to 16.6% after 5 d; by 7 d, male mortality was less than or equal to 59.5%. Treated males were 77-79% as attractive as untreated males to untreated females. Flight activity of treated weevils was 45-56% of that observed in the control. In competitive mating studies, numbers of females mated by untreated males were significantly greater than treated males at a ratio of 1:1. When treated males outnumbered untreated males by more than 5:1, the number of matings to untreated females was significantly higher. A 20:1 ratio of treated males to untreated males was required to significantly reduce F(1) adult emergence. Sterility, mortality, and vigor were increased with this new method compared with the previous method that involved feeding diflubenzuron (100 ppm) for 5 d followed by 10 krad of irradiation