Effect of Hexaflumuron on gustation and reproduction of adult boll weevil

Authors: Lopez, Juan De Dios; Latheef, Mohamed - Ab; Hoffmann, Wesley

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2008
Publication Date: 1/4/2009
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2009. Effect of hexaflumuron on gustation and reproduction of adult boll weevil. Southwestern Entomologist. 34:31-41.

Interpretive Summary: The boll weevil is an economically-important pest in cotton for which insecticides can be costly and, at times, not completely effective. A relatively new insecticide, hexaflumuron, was tested to determine if the insecticide suppressed or eliminated egg laying or larval hatch of boll weevils when the material was ingested. Results suggest that the use of hexaflumuron as a toxicant for suppression of boll weevils when ingested is limited because of inhibitory gustatory response and minimal reduction in larval hatch. The method of application of hexaflumuron, via ingestion, provides an additional tool for researchers that can lead to further analyses of new insecticides, which may be effective against boll weevils.

Technical Abstract: The efficacy of hexaflumuron was evaluated in the laboratory against boll weevil, Anthonomus grandis grandis Boheman, captured in pheromone-baited traps for gustatory response and reproduction of the insect. Hexaflumuron is an insect growth regulator which inhibits chitin synthesis and disrupts insect cuticle formation during molting. The intent was to determine the effect of hexaflumuron on mortality and reproduction of the boll weevil when it is fed to the adults mixed in ppm active ingredient (wt:vol) with 10 % sucrose as a feeding attractant. Regardless of concentrations, weevils captured in pheromone-baited traps in the fall ingested significantly more hexaflumuron than those captured in the spring. Seasonal mean amount of hexaflumuron ingested by the weevil decreased significantly with concentrations (adjusted R-squared = 0.82). Hexaflumuron significantly depressed gustatory response at 5 and 25 ppm, respectively, for fall- and spring-captured boll weevils. Hexaflumuron at 5 and 25 ppm significantly depressed oviposition and larval hatch, respectively, for both spring- and fall-captured weevils. However, reduction in larval hatch was minimal. Data suggest that the use of hexaflumuron as a toxicant for suppression of boll weevil when ingested is limited because of inhibitory gustatory response and minimal reduction in larval hatch. However, the method of application of hexaflumuron may be an important factor as a determinant of its effectiveness on weevil reproduction.