Evaluation of Bt cotton against tobacco caterpillar, Spodoptera litura (Fabricius) under laboratory conditions
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Date
2011
Authors
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Publisher
CCSHAU
Abstract
An experiment was conducted for evaluation of Bt cotton against Spodoptera litura
(Fabricius) during the year 2010-11 under laboratory conditions in CCS Haryana Agricultural
University, Hisar. Six genotypes namely Ankur Jai Bt, Ankur Jai BGII, Ankur Jai non Bt, RCH 134 Bt,
RCH 134BGII and RCH 134 non Bt were used for studying biological parameters viz., larval survival,
larval weight, larval period etc. at various days after sowing (DAS). At 60 and 90 DAS, BGII
genotypes were observed most effective but survival larvae were increased at120 and 140 DAS. Ankur
Jai non Bt was observed most preferred genotype among all six genotypes. Larval weight was observed
minimum on both the BGII genotypes throughout the investigation but an increased was observed after
120 of crop sowing. Similar trends were observed in larval period, pupal period, pupal weight and adult
emergence on BGII genotypes. All the parameters were increased after 120 DAS. Ankur Jai Bt was
preferred more by S. litura throughout the observations. RCH 134BGII and Ankur Jai BGII showed
good control of S. litura . There might be low production of Cry 2Ab in BGII genotypes that was the
reason for its decreasing effectiveness. Consumption utilization studies were also conducted at 65, 95,
125 and 145 days after sowing of crop. At 65 and 95 DAS, growth rate, efficiency of conversion of
digested food and efficiency of conversion of digested were observed minimum on BGII genotypes.
Consumption index remained non significant among all the genotypes upto 125 DAS observations it
revealed BGII had no feeding deterrent. Assimilation efficiency / assimilation digestibility remained
higher for BGII genotypes reason for this was unknown. After 125 DAS decreasing expression of Cry
2Ab was observed as all the parameters starts showing positive effects. At 145 DAS, a combine effect
of ageing and reduced Cry 2Ab was observed. In case of ovipositional preference under choice
conditions, females of S. litura showed no difference between BGII genotypes and other genotypes
under investigation. Leaves were preferred more over flowers/bracts and bolls for egg laying by S.
litura females.
Description
Keywords
Genotypes, Biological phenomena, Cotton, Animal developmental stages, Eggs, Sexual reproduction, Developmental stages, Sowing, Transgenics, Spodoptera litura