Evaluation of certain leaf extracts against red spider mite, Oligonychus coffeae Nietner (Acarina: Tetranychidae) infesting tea

Abstract

Leaf extracts of some common plants such as Vitex negundo (Linn. & Paracetamol), Gliricidia maculata (HBK), Wedelia chinensis (Osbeck), Morinda tinctoria (Roxb) and Pongamia glabra (Vent) were evaluated for their acaricidal activity against the red spider mite, Oligonychus coffeae, in the laboratory using the leaf disc method under controlled conditions. Leaves collected from the above mentioned plants were shade-dried followed by oven drying (at 60°C) and were milled in an electric blender. After this, the powder was taken for the preparation of the concentrations required for the various bioassays. Aqueous extracts were prepared and their effects on the mortality of adults and eggs and as oviposition deterrents were assessed after spraying and were compared with an untreated control. All tested plant extracts showed varying levels of effect on red spider mite compared with the untreated control. Among them, the aqueous extracts of M. tinctoria and P. glabra had maximum ovicidal action, ovipositional deterrence and 100% adult mortality.

Keywords:

• bioassay
• leaf extracts
• Oligonychus coffeae
• tea

Acknowledgements

The authors are grateful to Dr. P. Mohan Kumar, Director, UPASI Tea Research Foundation, for providing the facilities.