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<p>The two-spotted spider mite, <i>Tetranychus urticae</i> Koch, is a highly destructive and globally distributed pest that infests a wide range of agricultural and horticultural crops. Chemical acaricides play a crucial role in managing <i>T. urticae</i> infestations; however, the mite has developed significant resistance to multiple acaricides across various regions, posing a challenge to effective control strategies, posing a challenge the effectiveness of control strategies. This study evaluates the resistance levels of twenty <i>T. urticae</i> field populations against fenazaquin, propargite, and spiromesifen, collected from carnation and rose fields in a key cut flower-producing district of Tamil Nadu. The J. Kolakombai 1 population exhibited the highest resistance to all three acaricides, with LC<sub>50</sub> values of 958.84&#xa0;mg/L for fenazaquin, 1229.44&#xa0;mg/L for propargite, and 2506.64&#xa0;mg/L for spiromesifen, corresponding to the highest resistance ratios (RR) of 506.01, 897.40, and 2021.48, respectively. Resistance levels varied across populations, with Bikkamara and Kairkombai also showing substantial resistance, while Bettati and Ketty populations exhibited the highest susceptibility. Enzyme assays indicated a significant role of detoxification enzymes in resistance. A significant positive correlation was observed between resistance levels to all three acaricides, indicating potential cross-resistance (Pearson correlation). Several detoxification enzymes showed significant increase in the most resistant population relative to the most sensitive ones. The highest mixed-function oxidase (MFO) activity was observed in J. Kolakombai 1 (20.67 ± 0.69 nmoles/min/mg), exhibiting a 14.99-fold increase over a susceptible naive laboratory strain. Similarly, glutathione S-transferases (GSTs) (13.81 ± 0.40 µmoles/min/mg) and carboxylesterase (CarE) (9.17 ± 0.39 µmoles/min/mg) showed 18.75- and 14.19-fold increases, respectively. These elevated detoxification enzyme levels strongly correlate with high resistance to fenazaquin, propargite, and spiromesifen, underscoring their role in acaricide resistance mechanisms. This study may pave a preliminary platform for need-based decision-making on the replacement of existing acaricides with newer molecules of different mode of action or to manipulate the resistance mechanism in <i>T. urticae</i>.</p>

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Acaricide resistance and possible underlying biochemical mechanisms in the two-spotted spider mite, Tetranychus urticae Koch, on cut flowers

  • 期刊论文

  • 发表日期：

    2025年10月4日

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  • Sundaravadivel Sathiya Priya,
  • Ettiappan Sumathi,
  • Ramkumar Haran,
  • Perumal Renukadevi,
  • Marimuthu Murugan,
  • Thirumalaiandi Ramasubramanian,
  • K. K Kumar,
  • S. P Thamarai Selvi,
  • Sivakumar Kowsika

摘要

The two-spotted spider mite, Tetranychus urticae Koch, is a highly destructive and globally distributed pest that infests a wide range of agricultural and horticultural crops. Chemical acaricides play a crucial role in managing T. urticae infestations; however, the mite has developed significant resistance to multiple acaricides across various regions, posing a challenge to effective control strategies, posing a challenge the effectiveness of control strategies. This study evaluates the resistance levels of twenty T. urticae field populations against fenazaquin, propargite, and spiromesifen, collected from carnation and rose fields in a key cut flower-producing district of Tamil Nadu. The J. Kolakombai 1 population exhibited the highest resistance to all three acaricides, with LC50 values of 958.84 mg/L for fenazaquin, 1229.44 mg/L for propargite, and 2506.64 mg/L for spiromesifen, corresponding to the highest resistance ratios (RR) of 506.01, 897.40, and 2021.48, respectively. Resistance levels varied across populations, with Bikkamara and Kairkombai also showing substantial resistance, while Bettati and Ketty populations exhibited the highest susceptibility. Enzyme assays indicated a significant role of detoxification enzymes in resistance. A significant positive correlation was observed between resistance levels to all three acaricides, indicating potential cross-resistance (Pearson correlation). Several detoxification enzymes showed significant increase in the most resistant population relative to the most sensitive ones. The highest mixed-function oxidase (MFO) activity was observed in J. Kolakombai 1 (20.67 ± 0.69 nmoles/min/mg), exhibiting a 14.99-fold increase over a susceptible naive laboratory strain. Similarly, glutathione S-transferases (GSTs) (13.81 ± 0.40 µmoles/min/mg) and carboxylesterase (CarE) (9.17 ± 0.39 µmoles/min/mg) showed 18.75- and 14.19-fold increases, respectively. These elevated detoxification enzyme levels strongly correlate with high resistance to fenazaquin, propargite, and spiromesifen, underscoring their role in acaricide resistance mechanisms. This study may pave a preliminary platform for need-based decision-making on the replacement of existing acaricides with newer molecules of different mode of action or to manipulate the resistance mechanism in T. urticae.