Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 2006
Publication Date: October 5, 2006
Citation: Showler, A.T., Robacker, D.C., Salgado, E. 2006. Grandlure dosage and attraction of bollweevils (coleoptera:curculionidae). Journal of Economic Entomology. 99(5):1675-1681.
Interpretive Summary: The effect of grandlure dosage in laminated plastic pheromone dispensers has not been assessed. We used different dosages of grandlure in the dispensers placed in large capacity boll weevil traps, and plastic dispensers that were cut into quarters before and after aging them, to assess attractancy of each to boll weevils, and to measure the amounts of the pheromone components that were volatilizing. Lower dosages, either because of the amount incorporated in the dispenser, or because of attenuation of the pheromone components from aging, are less effective than greater dosages, and cutting the dispensers can 'revitalize' a dispenser by increasing escaping volatiles.
The effects of grandlure dosage on boll weevil attraction were assessed. Lures emitted more of each volatile pheromone component as the amount of grandlure increased, and traps collected more boll weevils under field and laboratory conditions as the amount of grandlure in laminated plastic strips was increased from 0 to 10, 30, and 60 mg. Spreading the point source of the lure by cutting the strip into quarters and positioning each quarter on separate corners of the large capacity traps in order to create an expanded source for the pheromone plume, however, resulted in fewer trap captures than traps with quartered lures all positioned on a single corner. The large capacity trap with the quartered lure on one corner also caught more weevils than the traps with an intact lure fastened to one corner. Although aging lure strips for three weeks reduced emissions of the four pheromone components and their attractiveness to boll weevils, cutting the aged lure into quarters resulted in greater emissions and attraction than lures that were aged intact or as quarters. Some pheromone components volatilized faster than others, resulting in time-related change in blend ratios, but the underlying factor in boll weevil attraction to grandlure strips was dosage, the amount of volatilized pheromone available for interacting with an adult boll weevil. It is possible that, if aged lures are cut sufficiently, they could be reused.