Residual Toxicity of Seven Insecticides on Boll Weevil, 1982

On Jul 19, a study was initiated at the Red River Valley Agricultural Experiment Station, Bossier City, LA, to evaluate the residual efficacy of several insecticides using a caged boll weevil technique. Plots were 2 rows x 30.48 m long on 1.02 m centers. A minimum of 2 buffer rows separated plots. Insecticides were applied with a CO2 powered hand sprayer equipped with 2 TX-4 spray nozzles per row. The sprayer delivered 74.8 liters/ha at 2.1 kg/cm2. Cotton-dacron cages (0.9 m x 0.65 m) were placed over individual cotton plants and tied securely near the base of the stalk. Adult weevils obtained from the Gast Rearing Facility at Mississippi State University were placed 25 weevils/cage in each of 2 cages per plot. After the weevils were caged, each cage was tied securely at the top. Weevils were placed in 1 set of cages (total of 18 cages, 2 cages/plot) immediately after spraying, in another set 24 h after spraying, and in the final set 48 h after spraying. Both the percent weevils alive and the percent mobile were recorded 48 h after the weevils were placed in the cages.