ABSTRACT

A sound understanding of the chemical ecology of the boll weevil, Anthonomus grandis Boheman, on cotton (Gossypium hirsutum L.) is important to efforts to improve pheromone trapping technologies. Recent reports of new methods of examining pheromone production by individual male weevils have indicated that most pheromone is not in the frass as was previously assumed. We used these new methods to evaluate the daily pattern of pheromone production of individual weevils, and the influence of time of food replacement on those patterns. Weevils fed daily at 0730 h (CDT) produced more pheromone (2.62 ± 0.30 μg/h) than weevils fed at 1530 h (1.66 ± 0.30 μg/h). Hourly pheromone production was highest during the intervals of 0730 – 1130 h (2.98 ± 0.37 μg) and 1130 – 1530 h (3.30 ± 0.37 μg), intermediate between 1530 – 1930 h (1.67 ± 0.31 μg), and lowest between 1930 – 0730 h (0.58 ± 0.16 μg). Weevils fed at 0730 h produced more pheromone during the 1130 – 1530 h period than weevils fed at 1530 h, but pheromone production by the two groups was more similar for other periods. Our results indicated less distinct daily patterns, and greater amounts of pheromone released during the scotophase, than were previously reported. Our results likely differ from the daily patterns of pheromone production occurring in the field because we did not simulate field temperatures. Still, they provide insights previously unavailable from the literature. These results also suggest additional study could further improve our understanding of the dynamics of boll weevil pheromone production.