Decade of neem research against rice insect pests in the Philippines
1987
Saxena, R.C. (International Rice Research Inst., Los Banos, Laguna (Philippines). Dept. of Entomology)
Complexities in the insecticidal control of rice insect pests and the problem of pest, biotypes adapted to resistant rice cultivars in the late 1970's led us to evaluate the potential of neem Azadirachta indica A. Juss. Neem seed derivatives - oil, cake, extracts or purified fractions, such as azadirachtin, were promising against sucking insects - the green leafhopper Nephotettix virescens (Distant), the brown planthopper Nilaparvata lugens (Stal), the whitebacked planthopper Sogatella furcifera (Horvath), and the rice bug Leptocorisa oratorius (Fabricius), and foliage feeders - the rice leaffolder Cnaphalocrocis medinalis (Guenee), the ear-cutting caterpillar Mythimna separata (Walker), and the rice armyworm Spodoptera mauritia acronynctoides (Boisduval). Insect feeding, growth and oviposition were inhibited on neem-treated plants. Contact with or ingestion of neem derivatives disrupted growth of insect pests but emergence of parasites was not affected. Predators, such as mirids and spiders were relatively insensitive to neem derivatives. In field trials application of neem derivatives reduced the incidence of insect-transmitted virus diseases and led to increased yields. Recently, a simple process has been developed for extracting neem pests "bitters" which are effective against several rice pest, and are nonphytotoxic, relatively photo-stable, and can meet the quality control standards. Concerted efforts are underway to promote large-scale propagation of neem in the Philippines.
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