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Title: AN EXPANDED EVALUATION OF INSECTICIDIAL TOXICITY TO COTTON FLEAHOPPERS

Author
item Lopez, Juan De Dios
item Latheef, Mohamed - Ab

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2005
Publication Date: 6/28/2005
Citation: Lopez, J.D., Latheef, M.A. 2005. An expanded evaluation of insecticidal toxicity to cotton fleahoppers. In: Proceedings of the Beltwide Cotton Conferences, January 4-7, 2005, New Orleans, Louisiana. 2005 CDROM.

Interpretive Summary: Cotton fleahopper is an important early season pest of cotton that is just starting to produce fruit. The first fruit (squares) that cotton plants produce contribute significantly to cotton yield as well as earliness which are very important to cotton producers. Insecticidal control of cotton fleahopper is still the major option available to producers to prevent damage so efficacy of insecticides is a very important consideration. Insecticides from different chemical classes were evaluated for toxicity to adult cotton fleahoppers using a vial technique in which insecticides at different concentrations were deposited on the inside of glass vials. Numbers of adults confined for 24 hours in the vials were then used to determine the toxicity level of each insecticide. Results show that there are highly toxic insecticides available to control cotton fleahoppers, which have a minimum effect on beneficial insect populations. Additionally, these data will be valuable in determining if the cotton fleahopper is becoming resistant to commonly used insecticides.

Technical Abstract: An adult vial test was used to determine the contact toxicity of several technical insecticides comprised of synthetic pyrethroids, organophosphates, neonicotinoids and carbamates to cotton fleahopper, Pseudatomoscelis seriatus (Reuter). Among the synthetic pyrethroids, bifenthrin was most toxic to cotton fleahopper with an LC50 (95% CLs) of 0.156 (0.135-0.179) µg/vial at 24 h. Among the organophosphates, dicrotophos with an LC50 of 0.189 (0.170-0.207) µg/vial was the most toxic compound to cotton fleahopper. The LC50s of bifenthrin and dicrotophos were not significantly different from each other. Among the neonicotinoids, thiamethoxam with an LC50 of 0.385 (0.272-0.515) µg/vial was the most toxic insecticide to P. seriatus. Data presented herein provide a measure of acute potency of various selected insecticides against P. seriatus. Since field performance is dictated by use rate and exposure, the current study may be limited in application. However, baseline data may be useful for comparison should suspicion of tolerance to these insecticides develop in field populations.