TOXICITY OF BOTANICALS AND SYNTHETIC INSECTICIDES AGAINST COTTON BOLLWORMS UNDER DIFFERENT IRRIGATION REGIMES

Abstract

Cotton, Gossypium hirsutum, is one of the most important cash crops in Pakistan. Insect pests are major limiting factor in crop production. The present research work was carried out to evaluate the toxic potentials of botanicals and synthetic insecticides against American bollworm, Helicoverpa armigera, Pink bollworm, Pectinophora gossypiellaa and Spotted bollworm, Earias insulana. Toxicity bioassays were conducted using plant oils (Neem oil, Jatropha oil, Castor-bean oil and G1-garlic oil) at 10, 20 and 30% concentrations against all three insect species. In case of infested bolls per plant by H. armigera infestation, the highest number of infested cotton bolls (averaging 2.01 per plant) was observed in BS-15 cotton variety planted with Jatropha oil under single lateral at 30 cm spacing, whereas the lowest count (averaging 0.49 per plant) was found with Profenofos+Cypermethrin under single lateral at 40 cm within the same cotton genotype. However, fewer infested bolls were noted in the CKC-3 cotton variety. For E. insulana infestation, the greatest number of infested cotton bolls (averaging 3.21 per plant) was seen in BS-15 cotton with garlic oil under double lateral at 30 cm spacing, while the lowest count (averaging 0.54 per plant) occurred with Lamdacyhalothrin under single lateral at 40 cm. In CKC-3 cotton, the highest infestation counts (averaging 2.92 per plant) were observed with garlic oil under double lateral at 30 cm spacing, and the lowest (averaging 0.39 per plant) with Lamdacyhalothrin under single lateral at 40 cm. P. gossypiella infestation resulted in the maximum number of infested cotton bolls (averaging 3.23 per plant) in BS-15 cotton with garlic oil under double lateral at 40 cm spacing, while the minimum (averaging 0.58 per plant) was recorded with Profenofos+Cypermethrin under single lateral at 40 cm. In CKC-3 cotton, the highest infestation counts (averaging 2.92 per plant) were noted with garlic oil under double lateral at 30 cm spacing, and the lowest (averaging 0.37 per plant) with Profenofos+Cypermethrin under single lateral at 40 cm. Regarding crop water productivity was highest (0.19 kgm^-3 ) in case of CKC-3 under drip irrigation plot compared with corresponding flood irrigated plot. Hence, integrated use of botanicals and the synthetic insecticides could be useful for effective control of the three cotton bollworms leading to maximization of the cotton yield.