Detection and biochemical characterization of acaricide resistance in field populations of tea red spider mite, Oligonychus coffeae (Acari: Tetranychidae), in Assam tea plantation of India

ABSTRACT

The red spider mite, Oligonychus coffeae, (RSM) is one of the most damaging pests of tea in most tea-producing countries. The use of synthetic acaricide, the main strategy for controlling RSM, has increased year by year. In this study, eight field populations of RSM were evaluated for resistance against five different acaricides (ethion, dicofol, propargite, fenazaquin, and fenpropathrin) using the leaf-dip method. The results showed that almost all the tested field populations had developed a high to very high level of resistance to ethion and dicofol. The highest level of resistance for RSM was found to ethion and dicofol with a resistance ratio of 134.27 and 65.38, respectively in the Cachar population as compared to the laboratory susceptible population. Propargite and fenazaquin were very effective against RSM in all tested populations, whereas a minor level of tolerance was evident against fenpropathrin at the recommended dose. Biochemical assays using detoxifying enzymes indicated that general esterase, glutathione-S- transferase, and cytochrome P450 monooxygenase activities were higher in all conventional field populations than in the susceptible population and also had a significantly positive correlation with the LC₅₀ values for ethion and dicofol. Synergism assays were therefore performed using ethion and dicofol in combination with common synergists like piperonylbutoxide (PBO), S.S.S.-Tributylphosphorotrithioate (DEF), and ethacrynic acid (EA). Results showed that mixing of PBO with ethion ensured about 36.73 times higher toxicity against RSM. DEF was moderately effective in revamping the effect of ethion whereas only EA was able to reduce the tolerance of RSM population to dicofol up to 11.71 times. The present studies infer that general esterase and cytochrome P450 monooxygenase may play a major role in imparting resistance to ethion whereas only glutathione-S-transferase plays an important role in dicofol resistance in RSM. The present study indicates the need for adopting integrated resistance management programmes to effectively control RSM in the tea plantations of Assam.

KEYWORDS:

• Red spider mite
• LC₅₀
• detoxifying enzyme
• synergist

Acknowledgments

The authors are thankful to the Director Tea Research Institute and DST-SYST (Code No. SP-YO-014-2015) for financial support and also garden managers of experimental tea estate. Thanks are also due to all research personal of DST-SYST project for data generation and analysis. Author is also grateful to Prof. Ananda Mukhopadhyay, University of North Bengal, India for critically going through the manuscript and offering good suggestions for the improvement of this paper.

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This article does not contain any studies with human participants or animals performed by any of the authors so not applicable.