natural-products-in-plant-pest-management

Global Scenario and Natural Products 111.5 Other Plant ProductsOther environmentally safe botanical pesticides are in use from plants,namely from Annona squamosa (seeds), Pongamia pinnata (seeds) and Vitexnegundo (leaf) (Hiremath et al., 1997). Some plant species are known tobe highly resistant to nematodes. The best documented of these includemarigolds (Tagetes spp.), rattlebox (Crotalaria spectabilis), chrysanthemums(Chrysanthemum spp.), and castor bean (Ricinus communis) (Duke, 1990).These plants may be recommended as intercropping plants to control thenematode population in soil through their exudates and leachates. In additionto protecting crops from infestation, many rainforest plants can be usedas insect repellents. Bright orange berries of Bixa orellana are effective indeterring biting insects, in addition to being used as a body paint and dye(Butler, 2009). In some of the members of Asteraceae, the photodynamiccompound alpha-terthienyl has been shown to account for the strong nematicidalactivity of the roots (Fig. 1.7a). However, no plant-derived productsare sold commercially for the control of nematodes. Strychnine formulationsare used in commercial rodenticides (Fig. 1.7b). Quassia amara (SurinamWood), belonging to the family Simaroubaceae, is a tree species naturallydistributed in Suriname and several tropical countries. Traditionally, the barkand leaves are used in herbal remedies and as medicine because the majorsecondary metabolites of this tree, quassin and neo-quassin, exhibit pharmacologicalproperties such as antimalarial, antifungal, anti-ulcerative, antiedimogenicand anticancer activity. The male reproductive system, particularlyspermatogenesis, sperm maturation and androgen biosynthesis, is highlysensitive to the metabolites of Q. amara, which would be useful for insect pestcontrol but may also affect male reproduction in non-target organisms. Therefore,their pharmacological effects on mammals should be determined beforerecommendation to avoid any handling problems with such chemicals. However,quassin has been recently assessed in trials in Australia to control pestsof Brassicaceae (Thacker, 2002).Some plants have been reported to contain insect growth regulatorychemicals (IGRs), which disrupt insect maturation and emergence asadults. Juvabione (Fig. 1.8a), found in the wood of balsam fir, was discoveredby accident when paper towels made from this source were used to lineinsect-rearing containers resulting in a suppression of insect development(a)(b)NHSSSNOHHHOHFig. 1.7. (a) α-terthienyl (b) Strychnine.