Qualitative damage of spider mites on selected medicinal plants and the corresponding biochemical changes

Abstract

Adaxial feeding by spider mite, Schizotetranychus baltazari on Murraya koenigii resulted in grey speckling, discrete peeling of leaf cuticle, greyish-white appearance, withering and defoliation, decreasing the leaf biochemicals viz., chlorophyll (15.82%), carbohydrate (42.48%), proteins (55.1%), crude fibre (43.71%), flavonoids (26.83%), phenols (75.00%), potassium (7.37%) and sodium (23.18%). But alkaloid (92.44%) and tannin (12.50%) contents found increased. Oligonychus mangiferus and Oligonychus thelytokus feeding in Ichnocarpus frutescens plants caused yellowish-white spots, drying, withering and premature leaf-drop with significant reduction in chlorophyll (55.88%) and flavonoids (64.71%), but alkaloids (220%) found increased. Feeding by Tetranychus hirsutus on Gymnema sylvestre produced orange to yellow spots, profuse webbings with numerous mites congregating for dispersal. Chlorophyll (15.89%), carbohydrate (90.90%), proteins (69%) and flavonoids (17.60%) found reduced, but alkaloids (14.30%) increased upon mite feeding. This increase in secondary metabolites attributed to induced response of the plants to feeding by spider mites questioning the utility of such leaves in herbal preparations and therapeutic use.