Effects of Stored-Product Beetle Infestation on Fat Acidity, Seed Germination, and Microflora of Wheat1

Abstract

The keeping quality of wheat and wheat plus dockage, which was infested by two stored-product beetles, Oryzaephilus surinamensis (L.) and Cryptolestes ferrugineus (Stephens), at 30°C and 70% relative humidity (RH) was determined over a 20-week period. The quality assessment criteria used were the changes in fat acidity values, seed germination, germ and endosperm damage, and fungal and bacterial infection. Heavy infestation (650 to 800 adults per 130g) by both insect species in wheatplus-dockage treatment resulted in significantly higher levels of infection by Penicillium and bacteria , which led to greater loss in seed germination than in noninfested wheat plus dockage. Fat acidity values in wheat-plus-dockage treatment increased significantly ( P < 0.01) only when it was infested with O. surinamensis , which produced significantly more adults and larvae than C. ferrugineus . Infestation by insects resulted in a decreased level of seed infection by fungi of the Aspergillus glaucus group. Damage to seed germ by C. ferrugineus exceeded damage by O. surinamensis; both species damaged the germ more than the endosperm.