The effect of wheat α‐amylase inhibitors incorporated into wheat‐based artificial diets on development of Sitophilus granarius L., Tribolium confusum Duv., and Ephestia kuehniella Zell

Abstract

Artificial grain kernels made from ground wheat grain, commercial wheat starch and wheat proteinaceous α‐amylase inhibitors were used as diets for adults of the granary weevil (Sitophilus granarius L). For the confused flour beetle (Tribolium confusum Duv.) and the Mediterranean flour moth (Ephesitia kuehniella Zell.), a friable mixture of the diets was used. The results of feeding trials showed that the survival of S. granarius adults was not correlated with the soluble proteins extracted from wheat and amylolytic activity located in this protein fraction. On the other hand, the weight of dust (the index of feeding intensity) produced during feeding depended on the presence of α‐amylase and trypsin inhibitors in wheat‐based diets. Ephesitia kuehniella larvae did not develop at all on a diet consisting of 50% wheat starch and 50% crude α‐amylase inhibitors from wheat. The same diet lengthened the development time of T. confusum larvae by 15.1 days. These results attest to the existence of a specific native enzymatic apparatus in the alimentary canals of these three grain pests. However, the highly active insect α‐amylase inhibitors appear to have a limited influence on the developmental parameters studied although some reduction of insects populations might be expected.