Avaliação do uso de terra de diatomácea contra a infestação de grãos de milho

Abstract

Grains postharvest losses in Brazil are estimated to be about 10%, mainly due to insects infestation. The species Sitophilus zeamais and Tribolium castaneum, which can be controlled by diatomaceous earth, are the principal insects infesting stored products. The objective of this study was to determine the effectiveness of different diatomaceous earth doses on the control of adult S. zeamais and T. castaneum in stored corn grains. Corn grains at 12, 14 and 16% humidity, with 92.35% of whole grain, were treated with 1000 and 2000 g t-1 doses of diatomaceous earth. Each treatment was  composed by five replications with 100 g of treated grains, or not (control), infested with 10 adult insects of each species. Three infestation periods were observed: 1 hour, 10 days and 20 days after the application of the product. The insect mortality and the technological grain analysis were verified 60 days after each infestation period. Higher mortality means (100%) were obtained with the lowest (12%) humidity content, and higher rotten grain levels (44.15% and 24.55%) were observed in control treatments of grains with the highest humidity contents (14 and 16%, respectively). Therefore, it ispossible to conclude that diatomaceous earth effectively controls S. zeamais and T. castaneum and reduces damages to stored grains, especially when humidity contents after harvest is around 12%.