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Influence of bacillus thuringiensis toxins on the development and midgut proteases in different larval instars of helicoverpa armigera

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Relation http://oar.icrisat.org/10921/
http://dx.doi.org/10.5958/0974-8172.2018.00145.1
10.5958/0974-8172.2018.00145.1
 
Title Influence of bacillus thuringiensis toxins on the development and midgut proteases in different larval instars of helicoverpa armigera
 
Creator Visweshwar, R
Akbar, S M D
Sharma, H C
Sreeramulu, K
 
Subject Integrated Pest Management (IPM)
Pest Management
Helicoverpa
 
Description Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is one of the most important pest worldwide.
Bacillus thuringiensis (Bt) toxins have used as a biopesticide or deployed in transgenic plants for
controlling this pest. We examined the biological activity of Cry1Ac, Cry1Ab and Bt formulation in
different larval instars of H. armigera with respect to larval development and proteolytic activity to
pinpoint the most susceptible instar, and the insect response to ingestion of Bt toxins. In the presence
of Bt toxins, the larval mortality and weight loss increased in a dose-dependent manner, and the
maximum effect was observed in neonates. Active Cry1Ac toxin resulted in greater mortality and
weight loss in all the larval instars. Total protease, trypsin and chymotrypsin activities declined in the
presence of Bt toxins as compared to the untreated control in all the larval instars. Ten protease
isozymes were observed in the untreated control larvae in second, third and fourth instars. Maximum
protease isozymes inhibition was observed in Bt toxin fed neonates. Inhibition of protease activity
increased with the concentration of Bt toxins. In presence of Bt toxins, aminopeptidase activity increased
from II to IV instar and alkaline phosphatase activity decreased from II to III and then increased in IV
instar. The pathogenicity of Bt was greater in early larval instars of H. armigera than the later instars,
suggesting that application of Bt formulation or deployment of Bt toxins in transgenic plants should
be directed against the early larval instars.
 
Publisher Entomological Society of India
 
Date 2018-10
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://oar.icrisat.org/10921/1/Influence%20of%20Bacillus%20thuringiensis%20toxins%20on%20the%20development%20and%20midgut%20proteases%20in%20different%20larval%20instars%20of%20Helicoverpa%20Armigera.pdf
Visweshwar, R and Akbar, S M D and Sharma, H C and Sreeramulu, K (2018) Influence of bacillus thuringiensis toxins on the development and midgut proteases in different larval instars of helicoverpa armigera. Indian Journal of Entomology, 80 (3). pp. 960-970. ISSN 0367-8288