Repellent effect of pea (Pisum sativum) fractions against stored-product insects

Peas (Pisum satitvum) are toxic to some stored-product insects. The repelle nt effect of fractions of pea seed to stored-product insects was evaluated in multiple-choice tests in which wheat kernels were dusted with fractions rich in either protein, fibre or starch at 0.001 to 10% (wt:wt). There was a negative correlation between pea protein concentration and the number of adults found in grain for Cryptolestes ferrugineus and Sitophilus oryzae, b ut not for Tribolium castaneum. Pea fibre repelled C.ferrugineus adults but not S. oryzae and T. castaneum. Pea starch did not repel any of the insect s. One-week old and 6-week old C.ferrugineus were equally repelled by pea p rotein. Repellency was detectable I h after exposure. Cryptolestes ferrugin eus and S. oryzae did not become habituated to the repellent action of pea protein even after 4 weeks of exposure. Habituation was observed, however, when C.jerrugineus was exposed to pea fibre for 4 weeks. In a two-choice bi oassay (0 vs. 0.1% and 0 vs. 1% pea protein), the pea-protein-treated grain had significantly fewer insects (C. ferrugineus, S. oryzae, Sitophilus zea mais, T. castaneum, and Tribolium confusum) than untreated grain. The prope rties of the pea protein fractions seem well suited for developing a natura l stored grain protectant. Crown Copyright (C) 2001 Published by Elsevier S cience Ltd. All rights reserved.