Ovo-Larvicidal Activity of Selected Insecticides, 1988

A field evaluation was conducted at the Red River Research Station, Bossier City, La., to determine ovicidal activity and residual toxicity of selected insecticides and insecticide combinations against tobacco budworm on cotton. Plots were 4 rows by 30.5 m arranged in a randomized complete block with 4 replicates. Cotton was planted 25 Apr on 1.02-m centers. No insecticides were applied to the test area prior to this study. Insecticides were applied 16 Jun with a high-clearance sprayer equipped with a CO2 system for spraying small plots. Materials were applied in 11.4 liters water/acre at 60 psi with TX-3 hollow-cone nozzles spaced 50.8 cm apart. Eggs were collected 2, 24, 48, and 96 h after treatment. Egg samples consisted predominantly of newly laid white eggs (<1 d old) collected from the upper leaves and terminal area of cotton plants. The number of eggs collected for each treatment was 40, 40, 20, and 20 for the 2-, 24-, 48-, and 96-h samples, respectively. Eggs were brought into the laboratory where they were removed with a small section of foliage and placed individually in 1-oz plastic cups half filled with an artificial diet. Mortality to eggs and newly hatched larvae was determined 96 h after each sample collection. Eggs collected and reared to adults from the untreated control were identified as 93% tobacco budworms.