Residual Activity of Organophosphorus Insecticides in Soil as Tested against the Eye Gnat, Hippelates collusor

Abstract

The long term activity of 20 organophosphorus insecticides in soil was studied against Hippelates collusor (Townsend), the predominant species of eye gnats in the southwestern United States. Soil lots treated with three dosages of each material were stored in a glasshouse maintained at 88[degree][plus or minus] 2[degree] F. and bioassayed against the eye gnat at from 2- to 8-month intervals of storage. Trithion, Daizinon, Bayer 25141, Co-Ral, ethion, GC-4072, and Ethyl Guthion at the intermediate or high dosage levels manifested appreciable residual activity against the gnat after 6 to 8 months of storage. Bayer 22408, phorate, American Cyanamid Experimental Nematocide 18133, GC-3583, and GC-3582 showed a great deal of biological activity at the intermediate or high dosage levels after 2 months of storage, but were not active at later intervals of testing. The other materials, Methyl Trithion, Bayer 29493, Guthion, Di-Syston, ronnel, dimethoate, parathion, and Bayer 22684 did not, even at the highest dosage levels, show any appreciable residual activity when they were tested 2 months after storage. Chemical Definitions of Proprietary Materials: American Cyanamid Experimental Nema-tocide 18133 (O, O-diethyl O-2-pyrazinyl phosphorothioate); Bayer 22408 (O, O-diethyl O-naphthalimido phosphorothioate); Bayer 22684 (0-methyl-0-(2-chloroethyl)-0-(2-dichlorovinyl) phosphate); Bayer 25141 (O,O-diethylO-p-(methylsulfinyl)phenylphosphorothioate); Bayer 29493(O,O-dimethyl O-(4-methylthio-m-tolyl)phosphorothioate); Co-Ral (O-O-diethyl O-3-chloro-4-methyl-2-oxo-2H-l-benzopyran-7yl-phosphorothioate); Diazinon (O,O-diethyl O-(2-isopropyl-5-methyl-4-pyrimidyl) phosphorothioate); Di-Syston (0,0-diethyl S-2-(ethylthio) ethyl phosphorodithioate); Ethyl Guthion (0,0-diethyl S-4-oxo-1,2,3-benzotriazin-3 (4H)-ylmethyl phosphorodithioate); GC-3582 (0,0-diethyl-1-(2,5-dichlorophenyl)-2,2-dichlorovinyl phosphate); GC-3583 (0,0-diethyl-1-(2,5-dichlorophenyl)-2-chlorovinyl phosphate); GC-4072 (O,O-diethyl-1-(2,4-dichlorophenyl)-2-chlorovinyl phosphate); Guthion (O,O-dimethyl S-4-oxo-1,2,3-benzotriazin-3 (4H)-ylmethyl)phosphorodithioate); Methyl Trithion (O,O-dimethyl S-(p-chlorophenylthio)methyl phosphorodithioate); Trithion (O,O-diethyl S-(p-chlorophenylthio)methyl phosphorodithioate).