Median Lethal Time and Concentrations of Selected Insecticides against Third Instar Larvae of Plutella xylostella (Lepidoptera: Plutellidae).

Seven insecticides were selected to test their bio-efficacy against third instar larvae of diamond back moth, Plutella xylostella by employing “leaf-dip” method of bioassay. The efficacies of insecticides were assessed by using median lethal concentration (LC₅₀), median lethal time (LT₅₀) and cumulative larval mortality. The LC₅₀ and LT₅₀ of seven insecticides were chlorantraniliprole (7.21 ppm, 27.58 h), flubendiamide (13.99ppm, 30.33h), novaluron (74.25ppm, 40.82h), indoxacarb (95.47 ppm, 35.15h), Proton^® (391.74ppm, 32.35h), Hamla^® (420.72ppm, 28.21h) and profenophos (907.68 ppm, 36.19h), respecticely. The median lethal concentrations and median lethal time of seven insecticides increased with gradual decrease in concentration. The cumulative larval mortality was highest (100%) in chlorantraniliprole after 42 hours at 23.125 ppm. Among seven insecticides, chlorantraniliprole and flubendiamide were significantly better over other insectidcides against diamondback moth.