Bhabesh Deka , Azariah  Babu , Mridul  Sarmah

Department of Entomology, Tea Research Association, North Bengal Regional R&D Centre, Nagrakata-735225, West Bengal, India
Author    Correspondence author
Journal of Tea Science Research, 2017, Vol. 7, No. 4   doi: 10.5376/jtsr.2017.07.0004
Received: 23 Feb., 2017    Accepted: 16 Jan., 2017    Published: 28 Apr., 2017

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Deka B., Babu A., and Sarmah M., 2017, Bio-efficacy of certain indigenous plant extracts against red spider mite, Oligonychus coffeae, Nietner (Tetranychidae: Acarina) infesting tea, Journal of Tea Science Research, 7(4): 28-33 (doi: 10.5376/jtsr.2017.07.0004)

Leaf extracts of five different locally available plants such as Polygonum hydropiper L., Vitex negundo L, Tithonia diversifolia (Hemsl.) (wild sun flower), Artemisia vulgaris L and Clerodendrum infortunatum L were evaluated for their ovicidal and acaricidal activity against the tea red spider mite, Oligonychus coffeae, Nietner (Tetranychidae: Acarina) in the laboratory using the leaf disc method under controlled conditions. Leaves collected from the above mentioned plants were dried under shade, milled in an electric blender and extracted using two different solvents, hexane and methanol and prepared different concentrations viz. 1%, 0.75%, 0.50% and 0.25% by diluting in DMSO (dimethyl sulfoxide; an important polar solvent) and were used for different bioassays. The effects of the extracts on the mortality of adults as well as in the eggs were assessed after spraying and the results were compared with an untreated control. All tested plants showed varying levels of efficacy on red spider mite compared when with the untreated control. Among five plant species tested, methanol extract of Vitex negundo and Clerodendrum infortunatum showed maximum ovicidal action (66.71% and 57.45% respectively) and exhibited more than 90% adult mortality @ 1% conc. of both the hexane and methanol extract of Vitex negundo and Clerodendrum infortunatum after 24 h. 

Bio-control; Tea; Oligonychus coffeae ; Plant extracts