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The effects of α‐amylase inhibitors on insect storage pests: Inhibition of α‐amylase in vitro and effects on development in vivo
Author(s) -
Gatehouse Angharad M. R.,
Fenton Katherine A.,
Jepson Ian,
Pavey Deborah J.
Publication year - 1986
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740370804
Subject(s) - amylase , in vivo , in vitro , biology , insect , pest analysis , larva , digestive enzyme , biochemistry , callosobruchus maculatus , enzyme , food science , botany , microbiology and biotechnology
Protein α‐amylase inhibitors were prepared from wheat and their effects tested against insect storage pests both in vitro against the insect α‐amylases and in vivo in insect feeding trials. Inhibitor fraction A was found to inhibit porcine pancreatic α‐amylase but not insect α‐amylases, whereas fractions B, C and D (0.28) did not inhibit porcine pancreatic α‐amylase but were strong inhibitors of digestive α‐amylases from larvae of Tribolium confusum , a storage pest of wheat products, and Callosobruchus maculatus , a storage pest of legume seeds. Fraction D, which was a single polypeptide of M r 13 000 was the most effective inhibitor in vitro . It would appear that the degree of inhibition by the wheat α‐amylase inhibitor preparations can be correlated with the presence of the M r 13 000 (0.28) polypeptide since the purer this polypeptide the stronger was the inhibition; fraction A which contained two polypeptides of M r 60 000 and 58 000 caused no inhibition. The effects of fractions B and C on larval development were determined in insect feeding trials. With C. maculatus both fractions were toxic, their relative effectiveness being directly paralleled by their effectiveness observed in vitro . Only fraction C was tested against T. confusum in feeding trials. Despite this fraction being equally effective against both pests in vitro it had very little effect upon larval development of T. confusum in vivo , thus suggesting that this organism is able to detoxify the wheat α‐amylase inhibitors. As far as the authors are aware, this is the first time that the effects of identified inhibitor fractions have been monitored both in vitro and in vivo . The results, in contrast to previous proposals, suggest that selecting wheat varieties for high α‐amylase inhibitory activity may not be a very reliable criterion in selecting for insect resistance.