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Increased food utilization indices and decreased proteolytic activity in Helicoverpa armigera larvae fed sublethal Bacillus thuringiensis ‐treated diet
Author(s) -
Fathipour Yaghoub,
Sedaratian Amin,
Bagheri Abdoolnabi,
TalaeiHassanlouei Reza
Publication year - 2019
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/phen.12288
Subject(s) - helicoverpa armigera , bacillus thuringiensis , biology , bruton's tyrosine kinase , helicoverpa , protease , bollworm , proteolytic enzymes , larva , toxicology , food science , microbiology and biotechnology , enzyme , botany , biochemistry , bacteria , signal transduction , genetics , tyrosine kinase
The cotton bollworm Helicoverpa armigera is one of the most devastating insect pests. A set of protease enzymes allows this species to feed on different host plant species. Control measures in agriculture often involve the application of the pathogenic bacterium Bacillus thuringiensis subsp. kurstaki (Btk). In the present study, the effects of sublethal Btk doses are evaluated with respect to the food utilization indices and proteolytic activities of Helicoverpa armigera . Accordingly, the H. armigera larvae are fed with artificial diet containing sublethal Btk doses (LC 5 , LC 10 , LC 15 , LC 20 and LC 25 ) and a Btk‐free diet as control. All but one of the food utilization indices we measured is observed to increase significantly with increasing Btk doses. By contrast, the specific activity of total protease, chymotrypsin and elastase enzymes decrease significantly with an increasing Btk concentration. We conclude that Btk was not toxic to H. armigera larvae and any damage that it causes can be compensated for by H. armigera larvae via various mechanisms. In conclusion, increased nutritional indices in the larvae fed with Btk diet represent an important issue that needs to be considered to avoid the pest establishing Bt resistant populations. Meanwhile, the lack of effect of Btk sublethal concentrations on trypsin enzyme specific activity can bolster this challenge.