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Title: Mortality and reproductive effects of ingested spinosad on adult bollworm

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

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2010
Publication Date: 1/20/2011
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2011. Mortality and reproductive effects of ingested spinosad on adult bollworm. Pest Management Science. 67:220-225.

Interpretive Summary: Bollworms are a serious pest of cotton throughout the United States and must be controlled due to the economic damage they cause. Spinosad is both a contact and stomach poison for many caterpillar species, such as bollworms, and has low mammalian and environmental toxicity with reduced risk to wildlife compared with traditional insecticides. Studies were conducted to characterize the effect of spinosad on toxicity, proboscis extension, ingestion, reproduction, and survival of the offspring of bollworms when the spinosad was integrated into a feeding stimulant solution. Data suggest that spinosad is a useful toxicant in an attracticide formulation for use against the suppression of bollworm on field crops. The method of application of spinosad, via ingestion, provides an additional tool for farmers and researchers to control and mitigate damage to cotton caused by bollworms.

Technical Abstract: Bollworm adults (Lepidoptera: Noctuidae) upon emergence from their pupal cells actively seek and feed on plant exudates before they disperse and reproduce on suitable host plants. This nocturnal behavior of the bollworm may be exploited as a pest management strategy for suppression of the insect. The intent of the study was to determine in the laboratory whether or not spinosad when mixed with sucrose solution as a feeding stimulant and ingested by bollworm could influence mortality and reproduction of the insect. For feral male bollworm captured in pheromone-baited traps, the lethal concentration values (LC) for 24 and 48 h responses, respectively were 4.96 and 2.52 ppm. These values were significantly different from each other. Comparison of females which ingested sub-lethal concentrations of spinosad, and were paired with females fed 2.5 M sucrose solutions, showed that larval hatch of eggs was significantly depressed at 0.1 ppm, and was reduced to near zero at 2.5 ppm. No such reduction of larval hatch of eggs was observed when males ingested sub-lethal concentrations of spinosad, and were paired with females fed 2.5 M sucrose solutions. Fecundity was significantly influenced by the ingestion of spinosad by female bollworm. The survival of bollworm larvae to the pupal stage was significantly influenced by ingestion of spinosad by female bollworm. Data suggest that spinosad is a useful toxicant in an attracticide formulation for use against the suppression of bollworm on field crops. Field studies are required to validate the results obtained in the laboratory.