Campus Units

Entomology

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

6-5-2020

Journal or Book Title

Pest Management Science

DOI

10.1002/ps.5938

Abstract

BACKGROUND: The western corn rootworm is an economically important pest of corn. Management tactics include pyrethroid and organophosphate insecticides, which may be applied as a mixture to protect corn roots. The goal of our study was to characterize the effects of pyrethroids and organophosphates alone and in combination on larval corn rootworm mortality and injury to corn roots. We evaluated two insecticide combinations: tebupirimphos with β- cyfluthrin, and chlorethoxyfos with bifenthrin. Using a soil-based, laboratory bioassay, we exposed larvae to five concentrations of the pyrethroid alone, the organophosphate alone, the combined formulation, and a water control. We calculated LC50 values and co-toxicity factors to determine synergism or antagonism between organophosphates and pyrethroids. We also measured adult emergence and root injury in a field experiment that tested tebupirimphos alone, β-cyfluthrin alone, the combined formulation, and an untreated control.

RESULTS: Bioassay results indicated antagonism between the pyrethroid and organophosphate at most concentrations for both insecticide combinations. In the field experiment, tebupirimphos alone or in combination with β-cyfluthrin significantly reduced adult emergence and root injury compared to the untreated controls, but β-cyfluthrin alone did not differ from the untreated control for either metric.

CONCLUSIONS: These results suggest that, at the concentrations tested, the pyrethroid component of pyrethroid-organophosphate mixtures may not contribute to a reduction of rootworm emergence or root injury. While these pyrethroids may confer a management benefit for other pests, such as seedcorn maggot, the concentrations of pyrethroids present in current formulations of these mixtures are likely too low for effective rootworm management.

Comments

This is the peer reviewed version of the following article: St. Clair, Coy R., Edmund J. Norris, Kenneth E. Masloski, Joel R. Coats, and Aaron J. Gassmann. "Evaluation of Pyrethroids and Organophosphates in Insecticide Mixtures for Management of Western Corn Rootworm Larvae." Pest Management Science (2020), which has been published in final form at doi: 10.1002/ps.5938. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Copyright Owner

Society of Chemical Industry

Language

en

File Format

application/pdf

Available for download on Saturday, June 05, 2021

Published Version

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