COMPARISONS OF STANDARD AND EXTENDED-LIFE BOLL WEEVIL PHEROMONE LURES

Authors: Armstrong, John; Spurgeon, Dale; Suh, Charles

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2005
Publication Date: 4/1/2006
Citation: Armstrong, J.S., Spurgeon, D.W., Suh, C.P. 2006. Comparisons of standard and extended-life boll weevil pheromone lures. Journal of Economic Entomology. 99:323-330.

Interpretive Summary: Pheromone traps baited with grandlure are the basis for detecting and monitoring the boll weevil (Anthonomus grandis Boheman) in eradication programs. Operating procedures for eradication programs typically utilize one or more commercially available lures containing 10 milligrams (mg) of the four-component boll weevil pheromone (grandlure). Traps are inspected for weevils weekly, while the pheromone lure is replaced every two weeks. The Southeastern Boll Weevil Eradication Program has expressed interest in a newly available "superlure" for reducing the costs of post-eradication maintenance trapping programs. The superlure contains 25 mg of grandlure and 30 mg of eugenol, and is intended to reduce the labor costs of trapping by increasing the trap maintenance interval to three or four weeks. Our research indicates that the number of captured weevils did not always reflect differences among lure treatments indicated by assay of grandlure and eugenol content. Captured boll weevil numbers changed weekly across all trapping periods which confounded the capture results of standard and extended formulations. Extended lures performed as well as standard lures for a 2 week period, but the rate of release from superlures was usually less for the second week of operation compared to a renewed standard lure operated for 2 weeks. This study shows that a better understanding of the release of a superlure needs to be investigated before area wide adoption of the extended lure takes place in eradication or quarantine efforts.

Technical Abstract: The Southeastern Boll Weevil Eradication Program has proposed reducing maintenance program costs in eradicated zones by using an extended-life "superlure" in traps to detect populations of the boll weevil (Anthonomus grandis Boheman). However, superlure effectiveness has not been extensively evaluated. We compared the superlure (30 mg eugenol plus 25 mg grandlure) to a standard lure (10 mg grandlure) based on captures of weevils, and changes in lure pheromone content. Lure treatments (standard and superlure, replaced biweekly or not replaced) were compared in four month-long trapping periods. Captures of weevils did not generally reflect differences among lure treatments indicated by assays of lure contents. During the first two weeks of exposure, pheromone released by the superlure were generally comparable with those of the standard lure, but pheromone composition was more stable. During the second two weeks of exposure, the superlure usually released more pheromone than similarly aged standard lures, but less than half as much as the standard lure replaced biweekly. Based on numbers of captured weevils during the last two weeks of an extended trapping period, the superlure performed similarly to the standard lure replaced biweekly. However, corresponding pheromone releases by the superlure were less than those by the standard lure replaced biweekly. This inconsistency suggests that numbers of captured weevils alone may be inadequate for evaluation of pheromone formulations. Our results suggest that better understanding of the consequences of reduced pheromone release during an extended trapping period is needed before adoption of the superlure can be recommended.