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.