Efficacy of Surface Applications of Diaterra® against Sitophilus granarius L. (Coleoptera: Curculionidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Abstract

Abstract The present study investigated the insecticidal efficacy of Diaterra®, a native diatomaceous earth, against two significant stored grain pests, the grain weevil (Sitophilus granarius L., Coleoptera: Curculionidae) and the red flour beetle (Tribolium castaneum Herbst, Coleoptera: Tenebrionidae). To control of insect pests in stores or warehouses, grain industry relies on synthetic insecticides, but they have significant environmental and health risks. Diatomaceous earth offers a natural and environmentally friendly alternative. In addition, it is safe for wildlife, leaves no residues, and effectively controls pests. In the study, different doses (0.25, 0.5, 1, 2, and 4 g/m2) of diatomaceous earth were applied on concrete and wooden surface. A mortality of 100.0% was achieved for S. granarius on the wooden surface at a dose of 4g/m2 during the 96-hour and subsequent application periods, whereas for T. castaneum, this rate was recorded as 88.9% under the same dose and a 192-hour application period. On the concrete surface, a mortality rate of 100.0% was achieved for S. granarius at a dose of 4g/m2 after 120 hours of exposure. In contrast, for T. castaneum, this rate did not exceed 59.5% even with the same dose and a 192-hour application period. Under controlled laboratory conditions, a dose of 4 g/m2 of Diaterra® showed efficacy in managing S. granarius populations on wooden and concrete surfaces. The desired level of efficacy was not achieved for T. castaneum on either surface type. Based on the data obtained from this study, it can be concluded that prolonged exposure to diatomaceous earth leads to enhanced insecticidal efficacy against both S. granarius and T. castaneum on different surface types. This study emphasizes the importance of considering application duration and surface type as critical factors in maximizing the effectiveness of diatomaceous earth applications.