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STUDIES ON THE MOLECULAR CHARACTERIZATION OF INSECTICIDAL RESISTANCE IN Plutella xylostella (L.)

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Title STUDIES ON THE MOLECULAR CHARACTERIZATION OF INSECTICIDAL RESISTANCE IN Plutella xylostella (L.)
 
Creator SUNITHA, V
 
Contributor SINGH, T.V.K
 
Subject insecticides, pesticides, pesticide resistance, biological phenomena, animal developmental stages, selection, land resources, genetics, plutella xylostella, toxins
MOLECULAR, INSECTICIDAL RESISTANCE, Plutella xylostella (L.)
 
Description Insecticidal resistance and molecular characterization studies against third instar larvae of
DBM (Plutella xylostella L.) were carried out at Bt Lab, Dept. of Entomology, College of
Agriculture, Rajendranagar, Hyderabad and CICR, Nagpur. The larvae of DBM collected from
in and around Hyderabad of Andhra Pradesh were reared in the laboratory. The third instar
larvae obtained from field population were tested against acephate, cypermethrin, spinosad,
cartap hydrochloride and Cry2Ab by using leaf dip method of bioassay to calculate LC50 values.
The LC50 values of the acephate, cypermethrin, spinosad, cartap hydrochloride and Cry2Ab were
0.10 %, 0.08 %, 0.003 %, 0.01 % and 0.3 μg/ml, respectively, which were further used to
quantify the resistance in P.xylostella of parental generation (F0) from Andhra Pradesh,
Karnataka and Delhi populations.
The survivals from F0 generation were reared to next generation (F1). Resistance
development studies were carried out with third instar larvae of F1 generation by applying a
concentration of 80.00 % mortality in every generation for selection from F1 to F3 generations
against all the test insecticides and Cry2Ab toxin.
Studies on resistance revealed that 2.57 folds, 0.17 folds and 1.27 folds resistance was
developed against acephate, in F3 generation of Andhra Pradesh, Karnataka and Delhi
populations, respectively. In case of cypermethrin, 1.00 folds, 2.33 folds and 3.00 folds
resistance in F3 generation of Andhra Pradesh, Karnataka and Delhi populations, respectively.
Resistance studies further revealed development of 1.00 folds, 1.50 folds and 1.00 folds
resistance against spinosad, 1.33 fold, 2.28 and 1.26 folds resistance against cartap
hydrochloride, respectively, in F3 generation of Andhra Pradesh, Karnataka and Delhi
populations, respectively. In case of Cry2Ab toxin 1.98 folds, 1.49 folds and 1.35 folds
resistance was recorded in F3 generation of Andhra Pradesh, Karnataka and Delhi populations,
respectively.
The rate of development of resistance from F1 to F3 generations increased in all the three
populations against all the test insecticides (acephate, cypermethrin, spinosad, cartap
hydrochloride) and Cry toxin (Cry2Ab), except against acephate in Karnataka. The Andhra
Pradesh and Delhi populations did not developed resistance against spinosad from F1 to F3
generations.
The selected strains of acephate, cypermethrin, spinosad, cartap hydrochloride and
Cry2Ab exhibited no cross-resistance against emamectin benzoate, chlorantraniliprole and
flubendiamide, in all the three populations. Crosss resistance ratios by the selected strains were
below one which indicates that cross resistance was not developed against the selected strains of
acephate, cypermethrin, spinosad, cartap hydrochloride and Cry2Ab, except the Delhi
cypermethrin selected strain (D.CyR) which displayed development of cross resistance against
flubendiamide.
The degree of resistance acquired by the P.xylostella in field level was assessed by
continues spraying of the cabbage fields with double the dose of four conventional insecticides
i.e., acephate, cypermethrin, spinosad and cartap hydrochloride against the normal field dose
and the studies demonstrated that high resistance was developed against cypermethrin followed
by acephate, spinosad and cartap hydrochloride.
Molecular characterization of DBM was done with the survivals and controls of the test
insecticides (acephate, cypermethrin, spinosad, cartap hydrochloride) and Cry toxin (Cry2Ab) of
three regions (Andhra Pradesh, Karnataka and Delhi). The DNA was extracted and amplified
with ten primers. The highest number of amplicons was produced by the primer ABA-08 and
lowest was recorded with ABA-10 primer in Andhra Pradesh population. Karnataka population
showed highest polymorphism with primer ABA-13 and lowest with ABA-2 primer and in
Delhi populations highest polymorphism was found with primer ABA-13 and lowest with ABA-
09 primer.
The allelic distribution of ten primers with all the test insecticides and Cry toxin treated
survivals was studied. Based on the band scoring, ABA-02 primer produced a specific amplicon
of 750 bp which was present in control population of F0, F1, F2, F3 generations and was not
present in survivals of acephate treated population. ABA-04 primer produced specific amplicon
with 800bp size in survivals of the acephate treated population and was absent in control
population of Andhra Pradesh. The ABA-12 primer yielded specific amplicon with a size of
820bp in acephate and Cry2Ab treated survivals and which was absent in control population of
Delhi.The cluster analysis studies revealed that as the selection pressure increased, genetic
variation decreased.
 
Date 2016-06-07T13:39:18Z
2016-06-07T13:39:18Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66932
 
Language en
 
Relation ;D9244
 
Format application/pdf
 
Publisher ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY