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.