The effects of α‐amylase inhibitors on insect storage pests: Inhibition of α‐amylase in vitro and effects on development in vivo

Abstract

Protein a-amylase inhibitors were prepared from wheat and their effects tested against insect storage pests both in vitro against the insect a-amylases and in vivo in insect feeding trials. Inhibitor fraction A was found to inhibit porcine pancreatic a-amylase but not insect a-amylases, whereas fractions B, C and D (0.28) did not inhibit porcine pancreatic a-amylase but were strong inhibitors of digestive a-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, 13 000 was the most effective inhibitor in vitro. It would appear that the degree of inhibition by the wheat a-amylase inhibitor preparations can be correlated with the presence of the M, 13 000 (0.28) polypeptide since the purer this polypeptide the stronger was the inhibition; fraction A which contained two polypeptides of M, 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 a-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 a-amylase inhibitory activity may not be a very reliable criterion in selecting for insect resistance.

α-Amylase Inhibitor, Not Phytohemagglutinin, Explains Resistance of Common Bean Seeds to Cowpea Weevil

“…These data are consistent with an aAI impurity level of 18% (w/w) in the PHA-P preparation. We also confirmed that both the PHA-P preparation and purified aAI inhibited endogenous cowpea weevil midgut a-amylase activity using a crude cowpea weevil midgut preparation (data not presented) (7), while PHA-E and PHA-L failed to inhibit the endogenous cowpea weevil midgut a-amylase.…”

“…The bean aAI was purified as described (16). Assay of a-amylase activity was similar to that previously described (3,7). Assay of porcine a-amylase was performed by suitably diluting in reaction buffer the enzyme to give, in the absence ofinhibitor, hydrolysis kinetics in the linear range.…”

“…Cowpea weevil midgut preparations containing aamylase activity were suitably diluted and assayed as described above (3,7). RESULTS …”

A Multigene Family of Trypsin/α-Amylase Inhibitors from Cereals

“…Thus, insects which are able to feed on wheat endosperm have unusually high levéis of a-amylase (Gutiérrez eí al., 1990). High inhibitor concentrations in an artifitial diet were required to affect the development of larvae of Thbolium confusum, a storage pest of wheat producís, while quite low concentrations were effective against Callosobruchus maculatus, a pest of legume seeds (Gatehouse et al, 1986). More recently, transgenic tobáceo plants expressing the inhibitors BTI-CMe from barley or WMAI-1 (syn.…”

Expression of cysteine proteinase inhibitor genes (OCI and OCII) in transformed potato (Solanum tuberosum L.) plants

“…Inhibitori α-amilaze poreklom iz pšenice i pasulja, prisutni u veštačkoj dijeti, pokazali su toksičan efekat prema različitim insektima iz reda koleoptera i lepidoptera (Gatehouse et al 1986;Moreno & Chrispeels, 1989;Gutierrez i sar. 1993;Suzuki i sar.…”