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Direct toxicity and repellency of various technical-grade and formulated pyrethroid insecticides were tested against the twospotted spider mite, Tetranychus urticae Koch, in the laboratory. Direct toxicity (LC50)was measured by slide-dip tests while repellent activity was measured by mite dispersal (runoff50) from residues on broad bean, Vicia faba L., leaf disks. Technical-grade chemicals generally showed greater activity than formulated products. Comparison of activity among formulated pyrethroids showed that, for direct toxicity, deltamethrin 2.5 emulsifiable concentrate (EC) > cypermethrin 10 EC > flucythrinate 100 microemulsion > fenpropathrin 10 EC > fenvalerate 10 EC > fluvalinate 23.3 Aquaflow. For runoff, deltamethrin > fluvalinate > fenpropathrin > cypermethrin > f1ucythrinate > fenvalerate. The relative contribution of direct toxicity or runoff to any overall measure of acaricidal activity required the use of a suitable index. Therefore, we propose the ratio of LC50/runoff50 as an index of activity. This index gives an order of activity of fluvalinate > fenpropathrin > flucythrinate > cypermethrin > fenvalerate > deltamethrin.
Document Type: Research Article
Publication date: October 1, 1986
More about this publication?
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.