Control of Diamondback Moth by Application of Neem Extracts

Some extracts from neem seeds/neem seed kernels can give satisfactory to good control of diamondback moth, Plutella xylostella (L.), in cabbage and other crucifers. Water extracts prove most effective, sometimes even at low concentrations as low as 12.5 g of seed kernels per liter of water, provided the raw material contains sufficient azadirachtin. Neem could be developed into products suitable for IPM in cabbage, owing to their selectivity towards the natural enemies of pests. Neem application in cabbage can also have negative effects, such as a change of plant color and reduction of headsize. These disadvantages are considered of minor importance if heavy damage or even complete loss of the crop could be prevented by neem application. The use of neem seed kernel water extract is primarily of interest to the small vegetable farmers in developing countries as they can produce their own pesticide using locally available tools and raw material. The delayed effect of neem products, especially at low temperatures, may discourage farmers who are used to the quick impact of synthetic contact insecticides. The farmers’ resistance to slower acting products could be overcome by training. There seems to be no danger of diamondback moth developing resistance to neem products in the short term.