Millettia pinnata and Sesamum indicum seed oil based green pesticide formulations for the management of tea red spider mite, Oligonychus coffeae Nietner (Acari: Tetranychidae)

Abstract

Red spider mite, Oligonychus coffeae is an economically important pest of tea in major tea producing countries. The present study aimed to evaluate the efficacy of five plant oil based formulations viz.., SOF, MOF, SMOF1:1, SMOF3:2 and SMOF2:3 prepared by considering individual as well as combination of Sesamum indicum and Millettia pinnata seed oil at different ratios of 1:0, 0:1, 1:1, 3:2 and 2:3, respectively against eggs and adults stages of O. coffeae. The experiments were done following leaf dip and direct spray methods. LC50 values of different formulations viz.., SOF, MOF, SMOF1:1, SMOF3:2 and SMOF2:3 against O. coffeae (adult females) were 3807.10 ppm, 4672.88, 3248.98, 4155.57 and 4610.55 ppm, respectively. The formulations also showed significant ovicidal and growth inhibitory activity against O. coffeae. Two season field bio-efficacy results indicated that the formulations are highly effective against O. coffeae and were superior to commonly used chemical acaricide, ethion 50EC. No phytotoxic symptoms were observed on tea leaves treated with these formulations. Black tea manufactured from tea shoots treated with these oil formulations were free from any taint and scored good (6–8 in 10 scale) in organoleptic test. The data suggests that plant oils of M. pinnata and S. indicum seeds alone and in combinations have potential to manage tea red spider mite in the field and can be recommended for eco-friendly management of mite pest in tea.