Toxicity of Certain Insecticides to Three Lepidopteran Cotton Insects123

Abstract

Chevron 9006 ( O, S -dimethyl phosphoroamidothioate) and Bay 65258 ( O -ethyl S-methyl phosphoroamidothioate) were equally toxic to bollworms, Heliothis zea (Boddie), but Bay 65258 was more toxic to tobacco budworms, H. virescens (F.), than was Chevron 9006. Pennsalt TD-5063 (S-phenyl thiocrotonate) applied topically was more toxic to tobacco budworms than to bollworms but was ineffective as a conventional spray. Ultra-low-volume (ULV) and couventional sprays of General Chemical (GC-6506 (dimethyl p -(methylthio) phenyl phosphate) were initially about equally toxic to bollworms and tobacco budworms, but the residual toxicity of the ULV spray was greater. Topical applications of Bay 37344 (4-methylthio)-3,5-xylyl methylcarbamate), Bay S-2758 (4(methylthio)- m -tolyl methyl-carbamate), and Bay 37344 sulfoxide (4-(methylsufinyl)-3,5-xylyl methylcarbamate) were more effective against larvae of bollworms than against larvae of tobacco budworms, and Bay 37344 sulfone was toxic to larvae of tobacco budworms and bollworms when it penetrated the cuticle. The tolyl or xylyl phenyl homologue of Bay 37344 was more toxic than the phenyl, and the tolyl homologue was more toxic than the xylyl.