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Susceptibility levels of tobacco caterpillar, Spodoptera litura (Fabricius) populations to insecticides

KrishiKosh

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Title Susceptibility levels of tobacco caterpillar, Spodoptera litura (Fabricius) populations to insecticides
Ph.D.
 
Creator KARUPPAIAH V
 
Contributor Chitra Srivastava
 
Subject enzymes, insecticides, animal developmental stages, pesticides, cytochromes, toxicity, planting, detoxification, inorganic acid salts, pesticide resistance
 
Description The tobacco caterpillar, Spodoptera litura (Fabricius) is a polyphagous insect pest causes
economic damage to various field and horticulture crops. Significant changes in susceptibility
level of S. litura to different insecticides have been observed with different populations. Host
plant induced changes influence the sensitivity of the pest to insecticides as well as pesticide
detoxification enzymes. Due to development of tolerance to conventional insecticides new
insecticide could be effective in pest management programme. Larvae of S. litura collected from
Delhi, Sonepat and Varanasi from cauliflower field were bioassayed topically with profenophos,
quinalphos and cypermethrin. Along with, the variation in the detoxification enzymes
carboxylesterase, glutathione S-transferase and cytochrome P450 and acetylcholinesterase
activity among the populations was investigated. The effect of four different larval diets
(cauliflower, soybean, castor and artificial diet) on insecticides (profenophos and cypermethrin)
susceptibility and detoxification enzymes activity in S. litura also studied. Susceptibility of all
the three population of S. litura was evaluated to some newer insecticide viz., emamectin
benzoate, spinosad, flubendiamide, chlorantraniliprole, indoxacarb, bifenthrin, pyridalyl, and
insecticide mixtures polytrin C (profenophos+ cypermethrin) and koranda (cypermethrin+
chlorpyriphos).
Delhi and Varanasi population showed least susceptibility to profenophos, whereas
Sonepat population showed least susceptibility to cypermethrin. The significant variations in the
activity of detoxification enzymes viz., carboxylesterase (CarE), glutathione S-transferase (GST),
cytochrome P450 monooxygenase and acetylcholinesterase (AChE) were observed among the
populations. The elevated level of CarE (28.09 μmolmin-1mg-1 of protein) activity was observed
in Sonepat population. Varanasi population of S. litura had elevated level of GST (1.380
μmolmin-1mg-1) and cytochrome P450 (19.31 μmolmin-1mg-1 of protein) enzymes and incidently
it was found to be least susceptible to all the three insecticides tested. The activity of
cytochrome P450 and GST in Sonepat population were 19.07 μmolmin-1mg-1 and 1.155
μmolmin-1mg-1, respectively. Enhanced level of acetylcholinesterase activity observed in
Sonepat and Delhi population which showed better response to profenophos and quinalphos.
Partial sequence of carboxylesterase showed polymorphism at nucleotide level.
The larvae of S. litura reared on castor and artificial diet found to be more susceptible to
profenophos and cypermethrin compared to larvae reared on cauliflower and soybean.
Cypermethrin was observed to be less toxic to the larvae that were fed on cauliflower and
soybean and LC50 values were 6.40 and 1.98 times higher as compared to that of diet reared
larvae. The elevated activities of carboxylesterase (CarE), and cytochrome P450 (Cyt P450) was
observed in larvae reared on cauliflower and they found to be least susceptible to cypermethrin.
Glutathione S-transferase (GST) activity was higher in the larvae that fed on soybean and had
maximum LC50 to profenophos. The acetylcholinesterase activity was higher in the larvae fed on
artificial diet. The higher activity of CarE, GST and Cyt P450 among different host bred larvae
reflected their relations with susceptibility to insecticides. Larvae had elevated activity of CarE,
GST and cytP450 were found to be less susceptible to all the insecticides.
Variation in the susceptibility of three populations of S. litura was observed to newer
compounds. All the three populations were found to be more susceptible to chlorantraniliprole,
followed by emamectin benzoate and indoxacarb as compared to other insectidicides. However,
the population obtained from Sonepat showed more tolerance towards these novel molecules as
compared to Delhi and Varanasi population. At the recommended field dose, chlorantranilprole,
emamectin benzoate and pyridalyl scored the security index (SI) threshold value ≥1 for all the
three populations and they could be considered effective against third instar larvae.Thus, existing
variation in the pesticide susceptibility of S. litura, novel insecticide could be the potential
candidates than conventional insecticide in near future.
 
Date 2016-03-11T16:32:04Z
2016-03-11T16:32:04Z
2013
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/65097
 
Language en_US
 
Format application/pdf
 
Publisher IARI, DIVISION OF ENTOMOLOGY,NEW DELHI