Bioefficacy of Newer Insecticides against Major Sucking Insect Pests of Cowpea [Vigna unguiculata (Linn.) Walp.]

The repeated use of conventional insecticides to combat the sucking pests resulted in development of resistance to insecticides. Now, several newer insecticides with their novel mode of action are very effective at lower doses against target pests and safe to natural enemies.

The experiment was conducted during kharif, 2018 in a randomized block design (RBD) with 9 treatments including the untreated control and 3 replications. The observations on population of aphid, Aphis craccivora Koch, leafhopper, Empoasca fabae (Harris) and whitefly, Bemisia tabaci (Genn) were recorded early in the morning from (10 cm terminal shoot) for aphid and from three leaves, viz., one each from top, middle and lower canopy of the plant for leafhopper and whitefly one day before and 1, 3, 7 and 15 days after application of insecticides in both the sprays.

Out of eight insectcides evaluated against aphid, leaf hopper and whitefly imidacloprid 0.005 per cent was found most effective followed by thiamethoxam 0.005 per cent and acetamiprid 0.004 per cent in terms of per cent reduction in the population and seed yield. Azadirachtin 1.5 ml/l and malathion 0.05 per cent were least effective against these insect pests. The highest benefit cost ratio of 18.48 was obtained from imidacloprid 0.005 per cent treated plots followed by thiamethoxam 0.005 per cent (17.30), acetamiprid 0.004 per cent (9.73) and dimethote 0.03 per cent (7.42), vis-a vis, lowest (1.62) in the chlorantraniliprole 0.005 per cent treated plots.