natural-products-in-plant-pest-management

6 N.K. Dubey et al.Natural pest controls using botanicals are safer to the user and theenvironment because they break down into harmless compounds withinhours or days in the presence of sunlight. Botanical pesticides are biodegradable(Devlin and Zettel, 1999) and their use in crop protection is a practicalsustainable alternative. Pesticidal plants have been in nature for millionsof years without any ill or adverse effects on the ecosystem. Botanical pesticidesare also very close chemically to those plants from which they arederived, so they are easily decomposed by a variety of microbes common inmost soils. Their use maintains the biological diversity of predators (Grangeand Ahmed, 1988), and reduces environmental contamination and humanhealth hazards. Botanical pesticides tend to have broad-spectrum activityand are sometimes stimulatory to the host metabolism (Mishra and Dubey,1994). Botanical insecticides can often be easily produced by farmers andsmall-scale industries. Recently, attention has been paid towards the exploitationof higher plant products as novel chemotherapeutics in plant protection.Such plant products have also been formulated for their large-scaleapplication in crop protection, and are regarded as pro-poor and cost-effective(Dubey et al., 2009).NeemNeem (Azadirachta indica) is regarded as the ‘Wonder Tree’, ‘BotanicalMarvel’, ‘Gift of Nature’ and ‘Village Pharmacy’ in India. From prehistorictimes, neem has been used primarily against household and storage pests,and to some extent against pests related to field crops in the Indian subcontinent.Neem oil and seeds are known to have inherent germicidal propertiesand have been in use for Ayurvedic (herbal) medicines in India for a longtime. Burning neem leaves in the evening is a common practice in rural Indiato repel mosquitoes. Neem is widely grown in other Asian countries andtropical and subtropical areas of Africa, America and Australia. It grows wellin poor, shallow, degraded and saline soil. Neem can be considered as themost important among all biopesticides for controlling pests. Neem pesticidesdo not leave any residue on the crop and therefore are preferred overchemical pesticides. In the past decade, neem has become a source of naturalpesticide due to its non-toxicity, environmental safety and so on, therebyreplacing synthetic pesticides. Neem derivatives have been applied againstseveral species of storage pests and crop pests as leaves, oil, cake, extractsand as formulations in neem oil (Gahukar, 2000; Dhaliwal et al., 2004). Neempesticides are thus a potential alternative to chemical-based pesticides andtheir use can avoid the dumping of thousands of tonnes of agrochemicals onEarth every year.Neem-based pesticides are sold under trade names such as Margosan-O,Azatin Rose Defense, Shield-All, Triact and Bio-neem. They have been shownto control gypsy moths, leaf miners, sweet potato whiteflies, western flowerthrips, loopers, caterpillars and mealybugs as well as some of the plantdiseases, including certain mildews and rusts.