Diel Patterns of Pheromone Production in the Boll Weevil (Coleoptera: Curculionidae)

Detailed knowledge of boll weevil, Anthonomus grandis Boheman, chemical ecology on cotton, Gossypium hirsutum L., is needed to improve pheromone trapping methods. Recent studies using headspace collections have indicated that most pheromone is not in the feces as previously assumed. We used headspace collections to examine the diel patterns of boll weevil pheromone production and to determine whether the timing of food replacement influenced those patterns. Pheromone production of individual 9- and 11-d-old weevils was estimated during 4 daily periods (0730–1130, 1130–1530, 1530–1930, and 1930–0730 h) under temperatures of 27 ± 2°C and with a 13:11 (L:D) h photoperiod that began at 0700 h. Weevils fed daily at 0730 h produced more pheromone (2.83 ± 0.25 μg h−1) than weevils fed at 1530 h (1.95 ± 0.25 μg h−1), and 11-d-old weevils produced more pheromone (2.62 ± 0.22 μg h−1) than 9-d-old weevils (2.16 ± 0.23 μg h−1). Furthermore, weevils fed at 0730 h exhibited a clear diel pattern of pheromone production ...