Investigation of pheromone-based factors that may reduce capture of boll weevils in traps

Authors: Westbrook, John; Suh, Charles

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2010
Publication Date: 4/19/2010
Citation: Westbrook, J.K., Suh, C.P. 2010. Investigation of pheromone-based factors that may reduce capture of boll weevils in traps. National Cotton Council Beltwide Cotton Conference. p. 994-998.

Interpretive Summary: Boll weevil eradication programs rely almost exclusively on pheromone traps to detect boll weevils, assess populations, and indicate the need for insecticide treatment. However, instances have been reported recently in Medina Co., TX, where field infestations occur without prior detection by pheromone traps around these fields. Therefore, the initial quality and release rates of pheromone traps with lure dispensers were examined to insure the traps were releasing pheromone at a steady rate, and that the pheromone blend from the traps was similar to that produced by boll weevils in Medina Co., TX. The results showed an inconsistent initial level of pheromones between traps and a rapid decrease in pheromone released from the traps within 7 days of use, which when combined, likely contributed to inconsistent trap captures in the field. Weevils collected in pheromone traps, collected off of cotton plants, and reared from infested cotton bolls produced a similar pheromone blend to that used in the trap lures. This information will aid eradication program managers in developing responses to the use of pheromone lures and traps for detection of remnant weevil populations.

Technical Abstract: Boll weevil (Anthonomus grandis Boheman) eradication programs rely almost exclusively on pheromone traps to detect weevils, assess populations, and indicate the need for insecticide treatment. However, instances have been reported recently in Medina Co., TX, where field infestations occur without prior detection by pheromone traps around these fields. We investigated the initial quality and release rates of pheromone from lure dispensers, and the pheromone blend produced by weevils in Medina Co. within the Winter Garden cotton production area of Texas. Mean initial content of grandlure in dispensers ranged from 7.2 mg to 12.0 mg during seven evaluation periods. Overall, the mean release rate of grandlure ranged from 1.54 mg/d at 1d to 0.24 mg/d at 11-14 d of aging. Weevils collected in pheromone traps, collected off cotton plants, and reared from infested cotton bolls produced similar ratios (44:43:2:11) of the four components of grandlure. The results suggest that initial lure quality and release rate of grandlure, but not pheromone blend produced by weevils, may have contributed to isolated cases of reduced capture of weevils in traps. This information will aid eradication program managers in developing responses to the use of pheromone lures and traps for detection of remnant weevil populations.