Persistent toxicity of spinosyn and diamide against Spodoptera litura (F.) on cowpea and soybean

The persistent toxicity (PT) of three insecticides viz. spinetoram @0.01%, chlorantraniliprole @0.006% and flubendiamide @0.01% has been determined on cowpea (Vigna unguiculata L. Walp.) and soybean (Glycine max L.) against 4d old larvae of Spodoptera litura (F.). The order of persistent toxicity was same for both the crop plants at 72 hours after feeding (HAF) i.e. spinetoram @0.01% > chlorantraniliprole @0.006% > flubendiamide @0.01%. On cowpea plant at 48 HAF, spinetoram showed the maximum PT value but chlorantraniliprole and flubendiamide showed the same PT value and at 24 HAF the order of persistent toxicity was spinetoram > flubendiamide > chlorantraniliprole; on the other hand on soybean the order of persistence was as spinetoram > chlorantraniliprole > flubendiamide for all 24, 48 and 72 HAF. On cowpea spinetoram @0.01% was the most persistent insecticide with a PT value of 759.96 followed by flubendiamide @0.01% (597.24) and chlorantraniliprole @0.006% (575.00) at 24 HAF. After 72 HAF on the treated leaves, spinetoram again showed highest PT value of 1897.2 followed by chlorantraniliprole (1542.72) and flubendiamide (1279.98). On soybean, spinetoram @0.01% was the most persistent with a PT value of 740.16 followed by chlorantraniliprole @0.006% (PT= 491.60) and flubendiamide @0.01% (476.00) at 24 HAF. At 72 HAF, spinetoram showed the maximum PT value of 1954.32 followed by chlorantraniliprole (1554.24) and flubendiamide (1485.60).