Toxicity of Insecticides Against Sawfly Larvae. 1. Contact Toxicity of Oreganophosphates and Carbamates to Neodiprion pratti banksianae N. swainei and Pristiphora erichsonii12

Direct contact toxicity of seven insecticides, propoxur, Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), Sumithion® ( O, O -dimethyl O -4-nitro- m -tolyl phosphorothioate), amidithion, phosphamidon, dimethoate, and DDT was evaluated against larvae of the jack-pine sawfly, Neodiprion pratti banksianae Rohwer; the Swaine jack-pine sawfly, N. swaineii Middleton; and the larch sawfly, Pristiphora erichsonei (Hartig), in search of an insecticide alternate to DDT and to establish baseline toxicity data of the present populations of these species. A comparison of the relative susceptibility of the 3 species to the insecticides was made. Propoxur was the most effective carbamate and Sumithion was the most toxic oregano phosphate. Both carbamates were superior to the oregano phosphates, and DDT was the least toxic. P. erichsonii was relatively more susceptible to DDT and less susceptible to propoxur and Sumithion than N. p. banksianae and N . swainei. N. swainei was more susceptible than N. p. banksianae to most of the insecticides tested.