Effects of Chlorpyrifos andLambda-andGamma-Cyhalothrin on Suppression of Aster Leafhoppers,Macrosteles quadrilineatus(Hemiptera: Cicadellidae) in Spring Wheat1

Abstract

ABSTRACT Unexpected outbreaks of the aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), in wheat in the spring of 2012 across the Northern Plains of the U.S. prompted extensive applications of insecticides to suppress their populations. Aster leafhoppers are infrequent pests of wheat in the Northern Plains early in the spring, and data on insecticide efficacy for aster leafhoppers in wheat were unavailable at the time of the outbreak. Thus, our goal was to test several insecticides commonly used against key pests in wheat for their efficacy against aster leafhoppers. We examined the effects of chlorpyrifos and lambda- and gamma-cyhalothrin in greenhouse and field. These insecticides are not currently registered for suppression of aster leafhoppers in wheat, but they are used frequently to control potato leafhoppers in alfalfa. We found that all insecticides reduced numbers of aster leafhoppers four days after application (DAA) in the field, but not seven and 14 DAA, likely due ...