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United States Department of Agriculture

Agricultural Research Service

Title: Toxicity and Degradation of Fipronil Applied to Cotton for Control of Boll Weevils

Authors
item Mulrooney, Joseph
item Goli, Deepa - SOUTHERN TESTING & RES.

Submitted to: Pesticide Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 1999
Publication Date: N/A

Interpretive Summary: Ultra-low volume application of malathion has been the principal insecticide used to eradicate the boll weevil from Virginia to eastern Mississippi. However, its use has been opposed by some environmentalists and cotton producers because of its harmful effects on non-target organisms. Research was needed to evaluate alternative insecticides for use in eradication of the boll weevil. This research evaluated the toxicity and degradation of fipronil, a new insecticide developed by Rhone Poulenc. The relative toxicities to boll weevils and the degradation of fipronil metabolites was demonstrated. An ultra violet light protectant, Carrier 038, was evaluated as a means of inhibiting the degradation of fipronil. The results of this research clearly show that metabolites play a role in the toxicity of fipronil, especially metabolite II, and that ultra low volume application increased the longevity of fipronil on the plant surface. The combination of Carrier 038 and cottonseed oil as diluent played a significant role in prolonging the presence of fipronil on the plant surface. This research indicates that fipronil may have potential as an insecticide for use in the boll weevil eradication program.

Technical Abstract: Fipronil was applied to cotton by ground sprayer at ultra low volume (1.17 L/ha) and conventional (97 L/ha) spray rates. Carrier 038, an ultra violet light protectant, was evaluated as a means of increasing longevity in the field. Boll weevil mortality and residue analysis of fipronil and its metabolites at 0, 1, 2, 3, and 6 d after application were used to evaluate treatments. An evaluation of the toxicity of fipronil and metabolites to boll weevils was also conducted. The order of toxicity (LD50) of fipronil metabolites at 48 h was metabolite III> fipronil> metabolite II> metabolite I. Differences in percentage mortality between treatments did not occur until 3 d after application when the ULV + Carrier 038 treatment produced the lowest mortality (62%) while mortality in the other three treatments ranged from 90 - 92%. There were no differences in mortality between treatments at 6 d after application. Fipronil degraded slower when applied to cottonseed oil at 1.17 L/ha than when applied in water as a conventional application at 97 L/ha. Carrier 038 reduced the degradation of fipronil on cotton leaves when applied at ultra low volume.

Last Modified: 12/21/2014
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