Changes in O 2 , Co 2 and Microflora of Stored Wheat Induced by Weevils 1

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Abstract
Changes in oxygen and carbon dioxide concentration and fungal infection were recorded in small wheat bulks initially infested with eggs of the rice weevil, Sitophilus oryzae (L.), and the granary weevil, S. granarius (L.). Gas chromatographic monitoring showed similar trends of O 2 depletion and CO 2 buildup for both species. The lowest O 2 concentration (35.2 mg/liter, 2.8% by vol) and highest CO 2 concentration (379 mg/liter, 21.7% by vol) were recorded at the bottom of the bins having 10% infestation of grain with S. oryzae . For both species relatively more adults, in relation to the total number of infested kernels present, emerged from a 5% infestation than from a 10% one. Emergence of S. oryzae , both at 5% and 10% infestation levels, was higher than that of S. granarius . The bottom layers of the grain were less viable and more infected with the storage fungi Aspergillus and Penicillium , than the top layers. Infection by field fungi was smaller at all levels.