Biochemical basis of insecticide resistance in Spodoptera litura (Fabricius) on cole crops
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Date
2015
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Publisher
PAU
Abstract
Studies were conducted to monitor the magnitude of insecticide resistance in tobacco
caterpillar, Spodoptera litura against different insecticides viz., emamectin benzoate,
chlorantraniliprole, indoxacarb, spinosad, quinalphos and deltamethrin collected from
different vegetable growing areas of Punjab. Chlorantraniliprole with LC50 value of 0.029-
0.088 ppm and emamectin benzoate with 0.037-0.081 ppm were found to be most toxic
insecticides against all the tested population of S. litura followed by indoxacarb, spinosad,
quinalphos and deltamethrin. Resistance levels for quinalphos and deltamethrin ranged from
21.80 to 38.90 fold and 24.8 to 64.2 fold, respectively. Different synergists i.e. Triphenyl
phosphate (TPP), Diethyl maleate (DEM) and Piperonyl butoxide (PBO) at ratios of 1:1, 1:2,
1:4 and 1:6 were tested with deltamethrin to know their synergistic effect and evaluated
against three different populations of S. litura collected from Malerkotla resistant (MAL),
Hoshiarpur susceptible (HSP) and deltamethrin resistant Malerkotla selected strain (MAL-Sel
strain) by leaf dip method. The results obtained in the present study revealed that PBO at 1:4
had highest synergistic effect on the susceptible (HSP-3.91 fold) and MAL (8.24 fold)
followed by TPP and DEM (1:4). However, the stronger synergism of TPP (1:4) was 23.67
fold followed by PBO (21.30 fold) and DEM (18.26) at 1:4 respectively, in case of MAL-Sel
strain which suggests the involvement of esterases and monooxygenases in imparting
resistance to various insecticides. Selection with deltamethrin increased the activities of
esterases and monooxygenases by 3.58 and 3.91 times in S. litura proving their role in
pyrethroid mediated resisitance. Inhibition studies with quinalphos showed (2.4 times) higher
tolerance in Malerkotla selected (MAL-Sel) strain than susceptible one implying the role of
insensitive AchE in insecticide resistance. Activity of these enzymes and insensitivity of
AchE can be used as biochemical tools for monitoring insecticide resistance in S. litura.
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Keywords
insecticides, pesticides, enzymes, spodoptera litura, toxicity, pesticide resistance, animal developmental stages, inorganic acid salts, mechanization, land resources