Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2010
Publication Date: June 17, 2010
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2010. Effect of emamectin benzoate on mortality, proboscis extension, gustation and reproduction of the corn earworm, Helicoverpa zea. Journal of Insect Science. 10:Article 89. Interpretive Summary: The bollworm is an economically-important pest in corn and cotton for which insecticides are costly and, at times, not completely effective. New approaches are needed to control bollworm populations with reduced-toxicant material applied to crops. A low dose of a relatively new pesticide, emamectin benzoate, was mixed in a sugar solution and presented for feeding by adult bollworms (moths). This laboratory study assessed the effects of this toxic mixture on the probing, feeding, reproduction, and mortality response of the bollworm. Emamectin benzoate in low doses was found to be an effective toxicant against adult bollworms, and suppressed feeding and egg production when presented in sub-lethal doses. Because emamectin benzoate is not toxic to a broad range of beneficial arthropods, it is compatible with integrated pest management programs and can be incorporated in a reduced-toxicant formulation that controls adult bollworms to avert widespread infestations by this pest.
Technical Abstract: Newly emerged bollworm adults, Helicoverpa zea (Boddie) require carbohydrate source from plant exudates and nectars for reproduction. Adults actively seek such feeding sites upon eclosion in their natural habitat. We wanted to evaluate this nocturnal behavior of the bollworm for potential use as a pest management strategy for suppression of this insect. The intent of this study was to assess the effects of emamectin benzoate on bollworms when fed to the adults mixed in ppm active ingredient (wt:vol) with 2.5 M sucrose as a feeding attractant. We evaluated the effect of emamectin benzoate on toxicity, proboscis extension, gustatory response and reproduction of the bollworm in the laboratory. Emamectin benzoate is highly toxic to feral bollworm males captured in pheromone-baited traps with LC50 values (95% CL) being 0.718 (0.532-0.878), 0.525 (0.316-0.751), and 0.182 (0.06-0.294) ppm for 24, 48 and 72 h responses, respectively. Sub-lethal concentrations of emamectin benzoate did not significantly depress proboscis extension response of feral males and gustatory response of female bollworm. Sub-lethal concentrations of emamectin benzoate significantly depressed percent larval hatch of eggs and mating frequency of female bollworm. Larval survival to the pupal stage was significantly influenced by ingestion of emamectin benzoate by the female bollworm. Data suggest that emamectin benzoate is a useful toxicant in an attract and kill strategy against bollworm. Field studies are warranted to validate the results reported in this study.