Evaluation of certain non-conventional plant based oils against red spider mite of tea

Abstract

Aim: Red spider mite, Oligonychus coffeae is considered as one of the most severe and persistent pest of tea. To limit the use of synthetic acaricides against the pest and to promote alternative pest control strategies using natural products, the present study aimed to determine the anti-mite properties of seven plant based oils viz., castor oil, sesame oil, rose oil, olive oil, mustard oil, groundnut oil and karanja oil against O. coffeae. Methodology: Red spider mites were collected from a commercial tea garden of Jorhat, Assam, India. Bioassays were performed on adults and eggs of O. coffeae with 5 to 7 different concentrations of plant oils. Mortality data was expressed by Abbott's formula and lethal concentration of 50% mortality (LC50) was calculated using Finney probit analysis and expressed in ppm. Results: Among the plant oils, karanja oil was the most toxic adulticide followed by mustard oil and olive oil. The egg hatchability was significantly affected in all treatments with rose oil being most toxic ovicide among the plant oils followed by karanja oil and olive oil. Further, their bioefficacy was comparable to synthetic insecticide, ethion. Interpretation: The data suggest that the selected plant oils have potential to control tea red spider mite, and therefore could be effectively utilized in integrated pest management programme envisaged for tea mite.