Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2013
Publication Date: January 2, 2014
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2014. Toxicity and feeding response of adult corn earworm (Lepidoptera: Noctuidae) to an organic spinosad formulation in sucrose solution. Pest Management Science. 2(1):33-41. Interpretive Summary: Natural insect control products are effective against corn earworm larvae in organic crops, but the utility of these natural products for controlling corn earworm moths is unknown. Studies were conducted to assess the efficacy of Entrust, a natural insect control product formulated from the spinosyn family of insecticides, to control corn earworm moths. A laboratory study revealed high mortality of corn earworm moths after ingestion of Entrust mixed with a sugar solution (feeding stimulant). Further, moth feeding response was not inhibited even at high doses of Entrust in the sugar solution. These results indicate that Entrust may be an effective component of a bait formulation as part of an attract-and-kill technology for corn earworm moths in organic farming systems.
Technical Abstract: Adult corn earworm, Helicoverpa zea (Boddie), feeds on plant exudates soon after emergence from pupa in their natural habitat, and thereafter disperses to suitable host plants for reproduction. The intent of this study was to determine if Entrust™, an organic formulation of spinosad, could be used in a behavioral-based pest management strategy to control H. zea in organic farming systems. In the laboratory, we evaluated the response of the corn earworm to Entrust mixed with sugar solution relative to ingestion, toxicity and proboscis extension. The sucrose solution served as a feeding stimulant and simulated the plant exudate. Lethal concentration of Entrust (LC50 with 95% CLs) for male corn earworm captured in pheromone-baited traps was 0.48 (0.43-0.53) mg L-1 for 24 h response. Mean lethal time was 2.56 ± 0.13 h with ingestion of Entrust at 50 mg L-1. A lethal dose of Entrust at 1000 mg L-1 neither inhibited ingestion nor proboscis extension response of the insect. A detailed study of the adult corn earworm in the laboratory relative to toxicity after ingestion of Entrust indicates that the pesticide has potential to control the insect when used in an insecticidal bait formulation as part of an attract-and-kill system. Field studies are needed to support the conclusion.