MINERAL CONTENTS OF CEREAL-GRAINS AS AFFECTED BY STORAGE AND INSECT INFESTATION

Insect infestation of wheat, maize and sorghum grains caused by Trogoderma granarium Everts and Rhyzopertha dominica Fabricius separately and in mixed populations resulted in substantial changes in the contents of calcium, phosphorus, zinc, iron, copper and manganese. At the highest infestation level (75%), R. dominica caused significant (P < 0.05) increases in the mineral matter of wheat and sorghum grains owing to loss of endosperm contents, but the increase due to T. granarium damage was not significant. On the other hand, R. dominica did not significantly change the mineral content of maize but a significant (P < 0.05) reduction was noticed at 75% infestation by T. granarium. Mixed populations of both species showed intermediate changes in the mineral contents of the three cereal grains. Storage of uninfested grains up to 4 months did not induce any appreciable changes in the levels of the six minerals. Variations in mineral content in relation to distribution in seed components and to feeding habits of insects have been discussed in the paper.