Location: Aerial Application Technology ResearchTitle: Toxicity of selected acaricides in a glass-vial bioassay to two-spotted spider mite (Acari: Tetranychidae)
|Latheef, Mohamed - Ab|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2014
Publication Date: 3/5/2014
Citation: Latheef, M.A., Hoffmann, W.C. 2014. Toxicity of selected acaricides in a glass-vial bioassay to two-spotted spider mite (Acari: Tetranychidae). Southwestern Entomologist. 39(1):29-36.
Interpretive Summary: The two-spotted spider mite can be an economically damaging insect in cotton since it reduces yield, fiber quality and seed health. Toxicity studies of commercially-available chemicals were done to determine which was most effective in controlling spider mites. There were significant differences in the effectiveness of the different chemicals used to control spider mites. These results will provide farmers and chemical applicators guidance when selecting chemicals to control and reduce spider mite populations.
Technical Abstract: Two-spotted spider mite (TSSM), Tetranychus urticae Koch, feeds on epidermal cells of cotton foliage, destroys photosynthetic cells, and reduces yields, fiber quality and seed germination. With a short life cycle, prolific fecundity, an arrhenotokous reproduction, and an ability to expeditiously digest and detoxify xenobiotics, TSSM has the propensity to develop resistance to insecticides. Despite its mobility, smallness of size, and difficulties associated with handling TSSM, this study that demonstrates that the 20-ml glass-vial bioassay, if handled skillfully and patiently executed, is a useful technique to evaluate contact toxicity of acaricides against adult mites in the laboratory. A colony of T. urticae was maintained on pinto beans, Phaseolus vulgaris L. in the greenhouse. Abamectin with a LC50 (95% CL) of 0.014 (0.01-0.02) µg per vial was 1006-fold more toxic to T. urticae compared to spiromesifen with a LC50 of 14.086 (7.592-42.371) µg per vial. The LC50 values of spiromesifen and propargite were comparable. Bifenazate was 10-fold more toxic to TSSM compared to dicofol. The order of toxicity of acaricides tested against two-spotted spider mite adult was abamectin > bifenazate >dicofol >propargite = spiromesifen. Data presented here are useful for developing a baseline contact toxicity data for adult TSSM, and for monitoring tolerance to the acaricides used for the control of this acarine pest on cotton in case such an event develops in Central Texas.