Selective Insecticides for Vegetable Leaf-Miner Control and Parasite Survival1

Abstract

A number of organphosphorus insecticides were tested on cantaloupes and peppers for control of a serpentine-leaf-miner ( Liriomyza Frick) and survival of a parasite ( Derostenus variipes , Cwfd.) to find insecticides with selective properties for use in an integrated control program. Ethion, Delnav® (2,3- p -dioxanedithiol S, S -bis ( O,O -diethyl phosphorodithioate 68%-70% and related materials)) and dimethoate gave excellent control of the leaf miner with residual toxicity lasting for 9 days or more on treated foliage. Parathion and Diazinon® ( O,O -diethyl O -(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate) were also effective, but lacked the residual control of the other insecticides. The highest parasite survival was obtained with Deluav, Dylox® (dimethyl 2,2,2-trichloro-1-hydroxyethylphos-phonate), Dibrom® (1,2-dibromo-2,2-diehloroethyl dimethyl phosphate), EPN, dimethoate, demeton and Am. Cyanamid 12008 ( O,O -diethyl S -(isopropylthio)methyl phosphorodithioate). Parathion, ethion and Diazinon, some of the more effective leaf miner control agents, were highly toxic to D. variipes . Delnav and dimethoate showed the greatest amount of selectivity for controlling L. munda and allowing survival of D. variipes . Both insecticides gave lasting residual control of the leaf miner and at the same time allowed 45% to 100% survival of the parasite larvae and pupae within the leaf. Insecticides with this degree of selectivity are necessary for the development of an integrated chemical-biological control program of vegetable leaf miners.