The antibiosis is one of the plant resistance mechanisms to insect attack in which plant defense proteins, like α- amylases inhibitors are involved. These inhibitor activities are found mainly in the seeds of leguminous and gramineous plant species. In the seed proteins of Phaseolus vulgaris L. var. Radical an α- amylase inhibitor has been reported that inhibits substantially (80%) the α- amylase activity of the coffee berry borer Hypothenemus hampei, and the α- amylases of mammals as well. It is necessary to search new α- amylase inhibitors from other plant seeds sources that have similar inhibitory effects on α- amylases but its activity being specifically toward midgut insect amylases. Eight protein extracts and one purified commercial preparation were obtained from different plant seeds and tested as inhibitors of coffee berry borer’s α- amylases using spectrophotometric and in-gel zymograms assays. Extracts from Zea mays L. and Brachiaria decumbens Stapf and the purified inhibitor of Triticum aestivum L. showed spectrophotometrically more than 50% of inhibitory activity on coffee berry borer α- amylases being also demonstrated by in-gel inhibition zymograms. While semipure extracts from B. decumbens and Z. mays did not show α- amylase inhibitory activities on α- amylases of mammals, the purified inhibitor preparation from wheat showed more than 50% of inhibition. Additionally the effect of both B. decumbens and Z. mays were evaluated upon the coffee berry borer instars breed in artificial diets, finding larval die percentage of 40 and 95 respectively. Therefore, these two species are a promissory source of genes coding for such inhibitory proteins that could confer resistance to the coffee berry borer.