ABSTRACT

Lichens are commonly used as spices and they have been used in traditional medicine from age-old days in various parts of India and world. The lichens have unique secondary metabolites when compared with higher plants and have found their uses in many fields such as medicine, dyes, cosmetics, deodorants, preservatives, and also in biopesticides. Large quantities of agricultural products are wasted every year due to insects, pests, and weeds. Various chemicals have been used to overcome this problem. The synthetic pesticides have an adverse effect on the health of human beings and other creatures and also lead to different types of environmental pollution. There are about 800 known metabolites from lichens such as salazinic acid, usnic acid, gyrophoric acid, stictic acid, and so on. Among these secondary metabolites, most are found to have pesticidal effect. Barbatic acid and barbatolic acids show antimicrobial activity. Diffractaic acid and evernic acids are known for their fungicidal effects. Hence, the present study aims at the biological control of pests and insects by utilizing the lichen substances as a potential source.