Treatment of rice with diatomaceous earth and effects on the mortality of the Red flour beetle Tribolium castaneum (Herbst)

Diatomaceous earth has been demonstrated in Australia, Germany, and the USA to protect stored products from infestation by insect pests. However, application of diatomaceous earth has rarely been used in Asian countries for the protection of stored grain from insect damage. These facts and the paucity of existing data from the tropics prompted the present study of storage with diatomaceous earth. We exposed rice treated with the diatomaceous earth product Fossil Shield® to infestation by Tribolium castaneum Herbst. During the dry season, when tests were conducted, the mean temperature was 29±2°C and relative humidity was 80±3%. The population of T. castaneum in rice was significantly reduced after treatment with Fossil Shield®. Diatomaceous earth at 1g and 2g per kilogram rice reduced population growth of T. castaneum to a coefficient of 0.27, and 0.02 respectively after 42 days. Fossil Shield® at 0.5g per kilogram rice increased the mortality of T. castaneum, but did not stop population growth.