Chemical-based integrated approaches for the management of tea red spider mite, Oligonychus coffeae Nietner (Acari: Tetranychidae) in tea plantations of sub-Himalayan North Bengal, India

Abstract

The tea red spider mite, Oligonychus coffeae Nietner (Tetranychidae), is considered one of the main phytophagous mite pests of tea plants in north-east India. To reduce the amount of synthetic chemicals in tea, a strategy of using optimal rates and effective spray practices has been developed. In laboratory tests, the 50% lethal concentration (LC₅₀ in parts per million (ppm)) values of ethion, dicofol, profenofos, propargite, fenpropathrin, fenazaquin and abamectin were 687.18, 534.04, 241.684, 90.256, 12.549, 4.319 and 2.405, respectively. Field rates of these acaricides were compared with 95% lethal concentration (LC₉₅ in ppm) values, and a decrease in the susceptibility of the test population to ethion, dicofol and profenofos was observed. There was no change for the newly introduced acaricides like fenazaquin, fenpropathrin, propargite and abamectin, which were effective at doses lower than the recommended dose. Of all the acaricides tested, abamectin was the most toxic and ethion was the least toxic. On the basis of LC₅₀ values, the descending order of ovicidal toxicity of the acaricides tested to O. coffeae eggs was fenazaquin, followed by profenofos, propargite, fenpropathrin, ethion, dicofol and abamectin. The data obtained in this study may be used as a tool in integrated pest management strategies that can effectively control the pest.

Keywords:

• Oligonychus coffeae
• acaricides
• LC₅₀
• LC₉₅
• relative toxicity
• ovicide