CONTROLLED AMBIENT AERATION DURING RICE STORAGE FOR TEMPERATURE AND INSECT CONTROL

Abstract

Rice (cv. Cypress) was harvested in September 2000 from a farm near Grady, Arkansas, placed in six, 600t(31,000bu) bins [each was filled with ~430 t (21,000 bu)], and dried gently from 18 to 13% moisture content (MC). Threeof the bins were equipped with an aeration control system activated by specific ambient air conditions in three cycles. Threeof the bins were aerated by the onsite, storage manager under his normal regimen. Grain temperatures were recorded at fourlocations within each bin. To monitor insect viability, small cages were filled with approximately 150 g of rice and 20, 1 to2weekold mixed sex adults of one insect species. The species that were tested included the lesser grain borer, Rhyzoperthadominica (Fauvel); the rice weevil, Sitophilus oryzae (L.); and the sawtoothed grain beetle, Oryzaephilus surinamensis (L.).Cages were removed at 5week intervals, and surviving and emerging insects were counted. Grain temperatures weresignificantly reduced through controlled aeration relative to the traditional, manual aeration. In addition, both live insectcounts and total emerged adult insects recovered from the cages were significantly lower (p < 0.05) within the bins treatedwith controlled aeration. The rice weevils were the hardiest of the insects tested, while sawtoothed grain beetles survivedthe least. This work indicates that controlled, ambient aeration can be an effective storage treatment against insects and maybe a useful alternative to chemical controls.