Insecticidal tests of Herpetogramma phaeopteralis (Lepidoptera: Crambidae) infesting St Augustine grass, Stenotaphrum secundatum

St. Augustinegrass, Stenotaphrum secundatum (Walter) is among the most widely used warm season turfgrass in Florida home lawns and tropical sod webworm, Herpetogramma phaeopteralis Guenée, (Lepidoptera: Crambidae) is one of the most serious pest. Insecticides are commonly used against a wide range of turfpests, including H. phaeopteralis. However limited information is available on relative toxicity of current insecticides against this pest. Our objectives were 1) determine lethal activity of chemical compounds amongst several classes against H. phaeopteralis larvae in the laboratory and 2) evaluate lethal and residual activity of the best performing insecticide under field conditions. The experiments involved six treatments: (1) 50WDG (clothianidin, Valent USA Corp., Walnut Creek, CA), (2) SC (Chlorantraniliprole, Syngenta Crop Protection Greensboro, NC), (3) Talstar Professional Insecticide “Talstar Pro,” 7.9% bifenthrin, FMC Corp.), (4) SP (Acephate, Valent U.S.A. Corp., Walnut Creek, CA), (5)  Bacillus thuringiensis variety kurstaki (Valent BioSciences Corporation, Libertyville, IL), (6) SC (Spinosad, Dow AgroSciences, LLC, Indianapolis, IN). Median lethal dose (LD₅₀) value of the anthranilic diamide chlorantraniliprole (4.53 ppm v/v) and acephate (8.54 ppm w/v) were significantly lower compare to other insecticides. Median lethal dose (LD₅₀) was highest for B. thuringiensis 342.03 ppm (w/v) and bifenthrin 282.67 ppm (v/v). I will report lethal and residual activity of above insecticides under field conditions.