Effects of neem based insecticides on Plutella xylostella (Linn.)

Abstract

A study on the effect of neem based insecticides on Plutella xylostella (Linn.) was conducted under laboratory conditions. Three neem based insecticides, Neemazal®T/S (1% EC @ 100 mg azadirachtin/liter), Neemix® (0.25% EC @ 25 mg azadirachtin/liter) and Neemexcel® (0.15% EC @ 15 mg azadirachtin/liter) were evaluated for their effects on biological parameters, pupal weight and nutritional indices of P. xylostella on cauliflower leaves. The concentrations tested were 5, 10, 15 and 20 ppm of active ingredient. The highest concentrations (15 and 20 ppm) of all three neem insecticides significantly affected the biological parameters of P. xylostella when compared with the lowest concentrations (5 and 10 ppm) and the non-treated control, Neemazal being the most effective. Results showed that development time was concentration dependent for all the neem insecticides. Neemazal significantly prolonged the development time at a higher concentration when compared with the other neem insecticides and non-treated control. Neemazal significantly affected the biological parameters and reduced the weight of pupa at 15 and 20 ppm concentration due to reduced consumption and utilization of food. However, no significant difference was detected between these two concentrations i.e. 15 and 20 ppm of Neemazal. Therefore, from the overall findings it could be concluded that the concentration of Neemazal i.e. 15 ppm could be utilized in IPM programs for P. xylostella in cauliflower crops.