Field study of the efficacy of an iranian inert dust insecticide on silo-stored wheat

In many bulk-stored grain situations, Inert Dust Insecticides (IDI’s) have proven to be the most efficacious and cost-effective products to control insect pests and employ for the pre- and post-treatment of the empty storage facilities, silos and grain-handling equipment. In this study, a field trial was conducted to evaluate the insecticidal efficacy of an Iranian IDI, Dryasil, for bulk wheat storage protection over a nine month term. Before starting the field trial, a laboratory test was conducted to confirm the efficacy of the Iranian IDI, as compared to that of an established, commercial IDI product, Silicosec, against Trogoderma granarium Everts, Rhyzopertha dominica (F.), and Tribolium confusum Jacquelin du Val. For the field trial, wheat was stored in a 100-tonne concrete silo, which has a history of storage insect-pests infestations in recent years. Dryasil was applied as structural treatment at a rate of 2 g/m 2 to the empty silo. The stored wheat received a 200 mm top-surface layer treatment and a 100 mm bottom layer treatment, both layers treated at a rate of 1 kg Dryasil/ton. Finally, the top surface was dressed with Dryasil at a rate of 100 g/m 2 . The effect of the treatment on the quality of the wheat at the end of the test period was also measured. The laboratory tests indicated that Dryasil and Silicosec have comparable efficacies against the tested species. The field trial demonstrated successful control of insect infestations for the 36 weeks storage term. The small increase in grain moisture content was a result of absorption from the more humid, ambient air. No adverse effects of Dryasil were detected on stored wheat properties.