MARIGOLD BIOPESTICIDE AS AN ALTERNATIVE TO CONVENTIONAL CHEMICAL PESTICIDES

Abstract

Marigold (Tagetes spp) which is considered to be a traditional medicinal plant, has significant therapeutic value and is used in treatment of a number of ailments. This review mainly emphasizes on the role of Tagetes as biopesticides especially as insecticide, mosquitocide, nematicide, bactericide and fungicide. The essential oils obtained from the aerial part of Tagetes mainly contain monoterpene hydrocarbons (ocimenes, limonene, terpinene etc) and acyclic monoterpene ketones (tagetones, dihydrotagetone and tagetenone) in addition to lower amount of sesquiterpene and oxygenated compounds. These components are mainly responsible for insecticidal, larvicidal and mosquitocidal property. On the other hand species of Tagetes also show strong nematicidal effect .Thus they can be used to suppress nematode species in the field by different techniques such as crop rotation or intercropping system or by exterting allelopahic effect. Tagetes can show a remarkable biochemical interaction known as allelopathy by producing a potentially bioactive component α-therthienyl that is mainly responsible for nematicidal action. This sulphur containing compound has nematicidal, insecticidal, fungicidal, antiviral and cytotoxic effect. The essential oil of Tagetes also shows strong bactericidal and fungicidal effect against a number of plant pathogenic bacteria and fungi. This review not only discusses the role of marigold as biopesticides especially as insecticides, mosquitocides, nematicides, bactericides and fungicide but also elucidates its ecofriendly potential to be used in the agricultural field as an alternative to chemical synthetic pesticides.