Susceptibilities of Adults of the Sweetclover Weevil to Certain Insecticides in the Laboratory

Abstract

Guthion® ( O,O -dimethyl S -(4-oxo-1,2,3-benzotriazin-3(4 H ) -ylmethyl) phosphorodithioate), at 1 oz; Bidrin® (3-hydroxy- N,N -dimethyl- cis -croton-amide dimethyl phosphate) at 4 oz; Bayer 39007 ( o -isopropoxyphenyl methylcarbamate), at 4 oz; and dimethoate, heptachlor, and malathion at 8 oz, when sprayed on adults of the sweetclover weevil, Sitona cylindricollis Fahraeus, as contact sprays at the rate of 4 gal/acre, gave significantly better control than the checks, and control equal to 8 oz of dieldrin, which was used as a standard for comparison. Where foliage was sprayed and later fed to the weevils, Bidrin, dimethoate, and malathion at 4 oz, Guthion at 6 oz, and Bayer 39007 at 10 oz gave control equal to the standard dieldrin treatment. These insecticides warrant field testing.