natural-products-in-plant-pest-management

Allelochemicals in Pest Management 143whitefly. Although the repellent effect declined in time and concentration,strong effects on the reduction of oviposition were found, while this effectlasts at least 12 days after application, dependent on concentration.Another example of commercially produced extracts with antifeedanteffects is represented by aromatic plants. For aromatic plants, substancesresponsible for the smell and those that may be isolated using distillationor supercritical extraction have been studied the most. This group of substancesincludes the mono- and di- sesquiterpenes, phenols and some otherhydrocarbons similar in structure (Pavela, 2008a).Many monoterpenes from plant sources have been evaluated as feedingdeterrents against insects (Koul, 1982). However, capillin, capillarin, methyleugenol and ar-curcumene isolated from Artemisia capillaris show promise asantifeedant compounds against cabbage butterfly larvae, Pieris rapae crucivora.The relative strong antifeedant activity of capillin and capillarin suggestthat the C=O carbonyl group instead of CH 2methylene group, a C≡C in aside chain and a lactone ring are some of the many factors that contribute tothe biological activity (Yano, 1987). Various derivatives of these base compoundssuch as methyl eugenol reveal that the 3,4-dimethyl group and1-substituent of 3,4-dimethoxy-1-substituted benzenes contribute to theantifeedant activity (Yano and Kamimura, 1993).Aromatic hydrocarbons show a significant direct insecticide activity,so consequently they have been best studied (Pavela, 2006b, 2008a,b). Nevertheless,antifeedant efficiency is connected not only with aromatic hydrocarbonsin aromatic plants, but also with other polyphenolic substancessynthesized by such plants as part of their defence strategy against diseasesand pests.These polyphenolic substances are currently being studied and becauseof their huge biochemical variety, it is highly probable that an antifeedantactivity will be discovered in the near future that would lead to practicalapplication.Recent results of biological activity studies of substances obtained fromEurasian region plants, too, provide evidence that primary research is necessaryand may lead to commercial application. Very strong, long-lasting antifeedantactivity of seed extracts and root extracts of Leuzea carthamoides plantsagainst the Colorado potato beetle (Leptinotarsa decemlineata) was found(Pavela, 2004a, 2006a) (Fig. 6.2. a,b). This antifeedant efficiency against theabove mentioned pest led to the formulation of a new product based on antifeedantactivity. The research on this aspect, which has been performed bothin our laboratory and in departments around the world, is thus providing itsfirst results.6.6 Prospects for Products Based on Antifeedant SubstancesMany feeding inhibitors from plant sources have so far given excellent resultsin laboratory conditions. In field situations only a few of them are satisfactoryalternatives to traditional pest management. The chemical control is usually