Protection of Wheat Seed with Diatomaceous Earth1

Laboratory tests were made to determine the relative effectiveness of dosages of diatomaceous earth proportional to 4, 6, and 8 1bs. per ton of grain in preventing or controlling insect infestations in wheat seed. Effectiveness of treatments was tested against the rice weevil, Sitophilus oryzae (L.); the granary weevil, Sitophilus granarius (L.); the lesser grain borer, Rhyzopertha dominica (F.); the confused flour beetle, Tribolium confusum Jacquelin duVal; the saw-toothed grain beetle, Oryzaephilus, surinamensis (L.); and the flat grain beetle, Cryptolestes pusillus (Schönherr). Tests were made under constant conditions of 80° ± 1° F. and 60% ± 5% relative humidity. Untreated control samples of wheat were completely riddled by the end of 6 months after initial exposure to insects. Results show that 4 Ibs. of diatomaceous earth per ton or grain would prevent infestations for 6 months, and 6 1bs. per ton would last 9 months. The 8-lbs.-per ton treatment was still effective when the experiment was terminated 12 months after initial exposure to insects. The results indicate that diatomaceous earth offers promise as a means of protecting seeds against insects, and it was concluded that more extensive trials should be undertaken with this material.