Development of combined use of neem (Azadirachta indica) and water management for the control of culicine mosquitoes in rice fields.

Crude neem products have earlier shown considerable promise for control of culicine mosquito vectors in rice fields as a by-product of their agricultural use as fertilizers, but suffer from disadvantages of bulkiness and lack of stability in storage. Relatively stable lipid-rich fractions of neem were shown to be as effective as good-quality crude neem products in control of breeding of culicine vectors of Japanese encephalitis, and also produced a slight but significant reduction in populations of anopheline pupae. Neem-based formulations coated over urea significantly increased grain yield, but used alone did not, whereas combining the use of neem-coated urea and water management by intermittent irrigation had a greater effect on grain yield than that of water management alone. The neem fractions were relatively cost-effective, and the combined water management and neem-coated urea strategy is acceptable to farmers, who are already aware of the benefits of the use of neem-coated urea, and of water management. This technology therefore has considerable promise as an environmentally benign method of rice-field mosquito control that could be sustainably implemented by farmers.