Quantitative Changes in Enzymatic Titer Offers Resistance against Flubendamide in Spodoptera litura Population Collected from Vegetable Crop Ecosystem of Rangareddy District, India
Sowmya K
*
Department of Entomology, College of Agriculture, PJTAU, Rajendranagar, Hyderabad, India.
Sunitha Devi R
AICC and Press, ARI, Rajendranagar, Hyderabad, India.
Rajanikanth, P
AINP on Vertebrate Pest Management, Rajendranagar, Hyderabad, India.
Rajeswari, B
Department of Plant Pathology, College of Agriculture, PJTAU, Rajendranagar, Hyderabad, India.
Kishore S.M
Department of Entomology, College of Agriculture, KSNUAHS, Shivamogga, Karnataka, India.
*Author to whom correspondence should be addressed.
Abstract
Aims: To understand the role of detoxifying enzymes, esterase, glutathione S-transferase (GST) and cytochrome P450 monooxygenase (MFO) in resistance development in Spodoptera litura against flubendamide
Place and Duration of Study: This experiment was carried out in the laboratory of the Department of Entomology and Central Instrumentation Cell, College of Agriculture, Rajendranagar, during kharif, 2022
Methodology: Quantitative changes in detoxification enzymes associated with flubendamide resistance were assessed in S. litura field populations from Chevella and Maheshwaram mandals and compared with a susceptible strain. Activities of esterase, glutathione S-transferase (GST) and cytochrome P450 monooxygenase (MFO) were estimated in third-instar larvae surviving LC₅₀ exposure of flubendamide using standard biochemical assays, as this surviving population acquired some resistance against the flubendamide treatment. Enzyme activities were statistically analyzed using ANOVA followed by a t-test at the 5% significance level with four replications.
Results: Exposure of third instar larvae of S. litura from Chevella and Maheshwaram to LC₅₀ of flubendamide resulted in significantly higher detoxifying enzyme activity compared to the susceptible population. Among the enzymes studied, mixed function oxidases (MFOs) showed the highest elevation (2.76–2.79 fold), followed by GST, while esterase activity increased only marginally. Strong positive correlations between resistance ratios and MFO (R² = 0.97) and GST (R² = 0.94) indicate their major role in flubendamide detoxification. These results suggest that enhanced MFO activity is the primary mechanism conferring tolerance to flubendamide in field populations of S. litura.
Conclusion: Understanding the enzymatic basis of resistance highlights the need for proper insecticide rotation and integrated pest management strategies to sustain flubendamide effectiveness with enhanced activity of MFO.
Keywords: Mixed function oxidase, esterase, glutathione-S-transferase, resistance, enzyme activity and detoxification