Velvetbean Caterpillar Ld*Jq Studies, 1973

Abstract

Abstract Twelve insecticides were tested against the velvetbean caterpillar. Four to six treatment rates plus a solvent-treated check were included for each insecticide tested. A 50% acetone-water mixture was used to dissolve and dilute technical grade carbaryl and acephate to the desired concentrations. Solutions of other chemicals were prepared by dissolving and diluting technical grade materials with pure acetone. All treatments were administered with a rmcroapplicator (Isco, Model M). Test insects from an established laboratory culture of velvetbean caterpillar were used. Larbae were supplied with fresh soybean leaves daily. Last-Instar velvetbean caterpillar larvae were apportioned randomly into groups of 10. Groups were weighed collectively, and the mean weight of larvae of each group was used to determine dosages of insecticides. Individuals were topically treated with 1 u! of solution applied to the thoracic dorsum. After treatment, larvae were placed in 236 ml screen-topped cardboard cups with fresh soybean leaves. These cups were then returned to the rearing room with 25�C, 50% RH, 12/12 h light/dark phoroperiod. Mortality counts were made 24 h after treatment. The method of Litchfield and Wilcoxon (1949) was used to calculate dosage-mortality curves and LD5Q values (expressed as ug of roxicant/g of insect).