Lawsonia inermis for management of Oligonychus coffeae, (Tetranychidae: Acarina) and its effect on biochemical parameters of tea leaves

Abstract

The study on bioefficacy of Lawsonia inermis against Oligonychus coffeae attacking tea was conducted at the Department of Entomology, Assam Agricultural University, Jorhat during 2018-20 revealed a dose and time-dependent mortality. L. inermis leaf water extract at 10.00% concentration was reported to cause as high as 80.00% adult mortality after 72 hours of treatment with a LC50 value of 2.085%. The leaf water extract of L. inermis also found to cause 14.85% egg mortality at 10.00% concentration as against 93.25% in the control. The study on possible changes in biochemical properties of tea leaves on application of L. inermis leaf water extract at LC50 values to control O. coffeae revealed an increase in reducing sugar content of 26.487 mg/100g as against 5.487 mg/100g in control. Similarly, the carotenoid content was found increased to 0.772 mg/g of tissue on application of water extracts of L. inermis as against 0.403 mg/g in control. In contrast, polyphenol content and photosynthetic pigments viz. chlorophyll a and chlorophyll b contents were found decreased upon application of water extracts of L. inermis under laboratory condition.