Joint toxic action of chitin inhibitor (lufenuron) and insecticides in the management of Plutella xylostella Linn. infesting mustard

The joint toxic action of a new chitin inhibitor, lufenuron, in combination with certain insecticides was studied against the diamond back moth, Plutella xylostella Linn., infesting mustard during 1995–96. The crop was sprayed twice at 18-day interval. The number of larvae/10 plants was recorded one day before spraying and on 2, 7, 12 and 17 days after spraying. Polytin C (0.066%) was the most effective two days after spraying, followed by cypermethrin (0.02%). After 7, 12, and 17 days, the combination, viz., lufenuron (0.025%) + cypermethorin (0.01%) was the most effective, followed by various combinations with lufenuron. Among the treatments, Bacillus, thuringiensis (0.15%) and neem oil (1%) were less effective consistently. Lufenuron (0.05%) was less effective on 2nd day after spraying but its efficacy improved by 7th day. The overall efficacy indicated that the combinations of insecticides with lufenuron were more effective, besides being less toxic to the natural enemies.