The toxicity of phenyl benzenesulphonate and some chlorinated derivatives towards eggs of certain tetranychid mites

Abstract

AbstractCertain chlorinated phenyl benzenesulphonates in current use for the control of mites infesting plants appear to function mainly as ovicides. 4‐Chlorophenyl 4‐chlorobenzenesulphonate and 2 : 4‐dichlorophenyl benzenesulphonate have been selected as being the most effective by American workers, whereas 4‐chlorophenyl benzenesulphonate appeared to be the most ovicidal of the esters examined in Britain.This paper describes the results of replicated assays of the ovicidal activities of phenyl benzenesulphonate and certain chlorinated derivatives towards the glasshouse red spider mite, and of leaf‐permeation studies involving summer eggs of the fruit tree red spider mite.4‐Chlorophenyl benzenesulphonate was found to be at least as ovicidal as 4‐chlorophenyl 4‐chlorobenzenesulphonate; differences between the five most potent compounds were significant at the LD50 level, but not at the LD95 level. Phenyl 4‐chlorobenzenesulphonate and the esters containing three or four chlorine atoms were of low or negligible activity.The ability of 4‐chlorophenyl benzenesulphonate to exert ovicidal action against eggs on the under surfaces of leaves after its application to their upper surfaces exceeded that of 4‐chlorophenyl 4‐chlorobenzenesulphonate and that of phenyl benzenesulphonate.Chlorination in the para‐position of the phenyl ring of phenyl benzenesulphonate enhanced ovicidal action, whereas para‐chlorination in the benzenesulphonic ring reduced it greatly. The effects of para‐chlorination in both rings do not appear to be merely a summation of the effects of chlorination in either ring.