The Toxicity of Insecticides to Larvae of Dioryctria abietella in Laboratory Screening Tests

Abstract

Laboratory screening tests were devised to evaluate the toxicity of 13 insecticides to last-instar larvae of a destructive pine cone moth, Dioryctria abietella (Denis & Schiffermuller). Emulsifiable concentrates of aldrin, BHC, chlordane, DDT, dieldrin, endrin, heptachlor, malathion, toxaphene, Diazinon® ( O,O -diethyl O-(2 -isopropyl-4-wethyl-6-pyrimidinyl) phosphorothioate), Guthion® ( O,O dimethyl S-(4-oxo-1,2,3-benzotrinzin-3-(4 H )-ylmethyl) phosphorodithioate), Perthane® (a mixture of diethyl diphenyl diehlorocthane (95%) and related reactionproducts (5%)), and Sevin®(1-naphthyl N -methylearbamate) were screened. Mature larvae were exposed to pine cones which had been dipped in a range of water dilutions or these concentrates. L.C .-90 values, estimated from concentration-mortality regression lines for the 96-hour exposure period, were used to assess the toxicity of each insecticide. At this mortality level the most effective insecticides, in decreasing order of toxicity, were endrin, BHC, Guthion, DDT, dieldrin, and Diazinon.