Comparison of toxicity of some synthetic insecticides against thrips (Thrips tabaci) on cotton crop under different irrigation regimes

Cotton is the main cash crop and back bone of agriculture. However, its yield is decreasing due to insect pests attack. Among them, sucking insect pests are serious problem in cotton and various agricultural crops. Hence, present research work was executed to assess the toxicity of some synthetic insecticides against Thrips tabaci in cotton crop. The research trial was executed with varied planting geometry under different irrigation regimes. Sowing of the cotton crop was done with plant to plant distance of 30 and 60 cm while row to row distance was 4 ft. apart. The plants were irrigated under single lateral and double lateral arrangements of drip irrigation while control plot was irrigated through conventional surface irrigation method. Results of relative incidence of thrips population on different irrigation plots showed that highest thrips population (19.43/plant) was noted in case of flood irrigated plot having plant to plant distance of 30 cm followed by in double lateral drip irrigation plot (15/plant) and single lateral plot (13.10 thrips/plant). Comparatively lower mean thrips population values; 16.30, 12.40 and 10.56 thrips/plant, respectively were recorded in experimental plot under 60 cm plant to plant distance. Toxicity bioassays revealed that highest reduction (75.27%) was recorded in spinetoram while lowest thrips population reduction (28.18%) was recorded in case of spinosad. It can be concluded that spinetoram can be effective tool for efficient control of thrips leading to augmentation in cotton crop yield.