Neem - a natural insecticide
The insect-repellent qualities of oil extracted from the fruit of the neem tree, and of cake from its residue after pressing, are being studied at the International Rice Research Institute (IRRI). This is part of a program me to develop biological pesticides that cause no ecological damage and scientists in several countries are cooperating with IRRI. Farmers in India, where neem is a native species, have long protected their crops with extracts of both its fruit and leaves. Scientists have discovered that neem derivatives repel 123 species of insects, including pests of stored grain. Neem oil and residues consist of a complex array of chemicals which exhibit diverse behavioural and physiological effects on insects. IRRI studies show that insects feed less, grow poorly and lay fewer eggs on pest-susceptible rice plants that have been sprayed with neem oil. Effects are similar with sucking insects, such as the brown planthopper, and chewing insects such as the rice leaffolder and the ear-eating caterpillar. In IRRI tests, five applications of a 25% neem oil emulsion sprayed with an ultra-low-volume applicator at 4 I/ha adequately protected a rice crop. Neem cake applied to rice fields has reduced nitrogen loss in experiments in India and at IRRI and neem may also encourage nitrogen fixation in rice. For more details, contact: Dr Ramesh C Saxena IRRI PO Box 933 Malina PHILIPPINES
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| Format: | News Item biblioteca |
| Language: | English |
| Published: |
Technical Centre for Agricultural and Rural Cooperation
1988
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| Online Access: | https://hdl.handle.net/10568/44852 |
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