Lannate Resistance in Beet Armyworm in Yuma

Abstract

A beet armyworm population was collected from spinach in Yuma, Feb 1996. This population was evaluated for resistance to Lannate. A range of Lannate dosages were prepared by disolving Lannate into acetone. A miroapplicator was used to topically apply the dosages. Dosage-mortality data were obtained from 3rd instar larvae held for 24 hr after treatment. The BAW population tested in 1996 had an LD₅₀ of value of433.34 μg-methomyl/g -worm, compared to a historical susceptible strain which had an LD₅₀ of 17.54 μg/g-worm, a 24.7 fold increase in resistance.