Evaluation of pirimiphos-methyl as a protectant for export grain

Wheat and corn were treated with pirmiphos-methyl at an intended concentration of 5 ppm during loading aboard a bulk dry-cargo vessel. The treatment applied to corn and wheat reduced insect infestations by 96% and 83%, respectively, although populations were low at the time of loading (> 1 insect per kg grain). Laboratory bioassays conducted with maze weevil, Sitophilus zeamais (Motschulsky), red flour beetle, Tribolium castaneum (Herbst), granary weevil, Sitophilus granarius (L.), and lesser grain borer, Rhyzopertha dominica (F.), showed that the applied dose was marginal and failed to prevent development of sub(1) progeny of all test insects.