Screening of Aphis Gossypii for Insecticide Tolerance, 1989

Abstract

Abstract Colonies of A. gossypii were assayed for insecticide tolerance using a leaf-dip test. Two colonies represented collections made from areas of control failures in Stoneville, MS, and Lawrence County, AL, and were reared in the greenhouse on DES 119 cotton 3 mon before a susceptible colony was established from aphids collected from Earlimart, CA. Cotton terminals were swirled 15 sec in water (control) or in a solution of formulated insecticide at a concentration causing approximately 90% mortality of susceptible insects: Lorsban 300 ppm, Thiodan 300 ppm, Capture 10 ppm, Metasystox-R 100 ppm, and Bidrin 100 ppm. Terminals were allowed to dry 45 min, placed in water wicks, and infested on leaf undersides using ventilated clip cages. Infested terminals were held at 80° F, 50% RH, and 14:10 L:D. Four replications (1 replication = 1 terminal) of 10 wingless adults/replication of similar size and color (green/black) from each colony were run. Mortality was determined 24 h later. Additionally, Lorsban and Thiodan were assayed using a laboratory spray table at field rates (1.0 lb and 0.33 lb (AI)/acre, respectively), calibrated to deliver 6 gal/acre (30 psi, TX 6 nozzle, 2 mph). Six replications of 10 aphids/replication were run for each treatment; caging, holding conditions, and test duration were the same as for dip bioassays.