PIRIMIPHOS-METHYL AS A PROTECTANT FOR STORED ROUGH RICE - SMALL BIN TESTS

Control of stored-product insects [Tribolium castaneum (Herbst), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Sitotroga cerealella (Olivier)] with pirimiphos-methyl applied at rates of 5, 10 or 15 ppm to rough rice was compared directly with the control obtained with 14 ppm malathion when the treated rice was stored in fiberboard drums and subjected to constant, heavy infestation pressure for 12 mo. Malathion was ineffective in protecting the grain from a malathion-resistant strain of the Angoumois grain moth, Sitotroga cerealella (Olivier). Pirimiphos-methyl at 10 and 15 ppm protected the rice from all insect infestation for 12 mo. Chemical residues in the rough rice and in all milling fractions were determined.