|Lopez, Juan DE Dios|
|Ree, Bill -|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 16, 2010
Publication Date: April 19, 2010
Citation: Lopez, J., Latheef, M.A., Ree, B. 2010. Toxicity of selected insecticides and insecticide mixtures to adult brown stink bug (Heteroptera: Pentatomidae). National Cotton Council Beltwide Cotton Conference. p. 985-990. Interpretive Summary: Brown stink bugs have become a key cotton pest as a result of decreased broad spectrum insecticide use attributed to widespread planting of Bt cotton varieties and boll weevil eradication in parts of the U.S. Cotton Belt. At present, control of brown stink bug is limited to use of insecticides; therefore, information on insecticidal toxicity is important. Adult brown stink bugs collected from cotton production areas were exposed to several commonly used, as well as, new pesticides. Commercially formulated mixtures of organophosphates, neonicotinoids, and synthetic pyrethroids were much less toxic than the technical mixtures prepared in the same active ingredient proportions indicating a reduction in toxicity due to formulation. Comparison of toxicity of some of the synthetic pyrethroids over the past few years indicate that tolerance to these insecticides is increasing. This information is important because it shows that insecticide selection, formulation and use are important considerations for maintaining sustainable insecticide effectiveness for control of brown stink bugs on cotton.
Technical Abstract: Glass vial bioassay were conducted to evaluate the toxicity of selected insecticides and insecticide mixtures to the brown stink bug (BSB), Euschistus servus (Say) collected from blacklight traps, cotton plants and weeds in farming areas in the Brazos Valley of Texas. Dicrotophos was 5- and 18-fold more toxic than acephate and chlorpyrifos, respectively. The order of toxicity for synthetic pyretrhoids was bifenthrin = zeta-cypermethrin = gamma-cyhalothrin > lambda-cyhalothrin > cypermethrin. Mixtures of technical insecticides prepared in the same proportions as formulations were significantly more toxic than their commercial formulations to BSB. The lack of potentiation of the mixtures may be due to absence of additivity or synergism in the composition of active and inert ingredients used in the formulations or the decreased concentrations of each component in the formulated mixtures. Tolerance to lambda-cyhalothrin and cypermethrin by BSB increased 2- and 3-fold, from 2005 through 2009, and 2006 through 2007 respectively. Increased tolerance to synthetic pyrethroids in field-collected BSB may have contributed to increased captures of BSB in blacklight traps in 2007 and greater and later occurrence on cotton and weeds in the Brazos Valley during 2009.