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Title: Boll weevil (Coleoptera: Curculionidae) response to and volitilization rates of grandlure when combined with varying doses of eugenol in the extended-life pheromone lure

item Armstrong, John - Scott

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2009
Publication Date: 4/8/2010
Citation: Armstrong, J.S. 2010. Boll weevil (Coleoptera: Curculionidae) response to and volitilization rates of grandlure when combined with varying doses of eugenol in the extended-life pheromone lure. Journal of Economic Entomology. 103(2):356-359.

Interpretive Summary: When the extended-life boll weevil pheromone was manufactured with 0, 10, 20, and 30 mg of eugenol, and boll weevil densities were high (i.e.>20/trap/week), the eugenol may increase the capture. Under current boll weevil densities that on average capture <1 boll weevil/trap/week, the eugenol does not perform better than lures without eugenol. Eugenol does not effect the longevity of the lure in terms of volatilization, and 4 weeks appear to be too long to expect an extended-life boll weevil lure to last, especially under the hottest weather of the summer.

Technical Abstract: Boll weevil extended-life pheromone lures, impregnated with 25 mg grandlure and 30 mg eugenol, are replacing standard pheromone lures (10 mg grandlure) in boll weevil eradication programs, to increase the changing interval from 2 weeks, to 3 or 4 weeks, which reduces labor and material costs. The addition of eugenol to the extended-life lure was never thoroughly evaluated to determine if it enhances the trapping of boll weevils by increasing attractiveness, or if it changes the rate of volatilization when combined with grandlure in the extended-life pheromone septa. Boll weevil trapping and pheromone quantitative analysis of extended-life pheromone lures manufactured with 0, 10, 20 and 30 mg of eugenol was conducted in the Rio Grande Valley of Texas under spring and summer conditions. Boll weevils responded positively to grandlure on 1 out of 12 trapping weeks when densities were high, but failed to respond to eugenol under low trapping densities of <2 weevils/trap/week. Weekly grandlure volatilization did not differ by eugenol dose, but was significantly different when evaluated over 3 different trapping periods a week within trapping period due to differences in ambient temperature. The amount of grandlure that remained after 4 weeks in moderate temperatures of spring was 13.1 +/- 0.19 mg (55.7% of original 25 mg content) compared to 5.5 +/- 0.15 mg remaining (22.8% or original 25 mg content) after for 4 weeks in summer heat. Weekly volatilization of grandlure for the summer trapping period was 9.8 +/- 0.32 mg for the first week, declining steadily to 1.0 +/- 0.09 mg by the 4th week of age. The data indicates that at high summer temperatures >30 degrees C, accumulative grandlure loss per week may be too high, leaving too little residual grandlure to effectively attract boll weevils at the end of a 3rd week of trapping. Eugenol plays no role in reserving or encouraging the release of grandlure, or in increasing boll weevil captures when boll weevil densities are low.