Insecticidal Efficacy of Silicon Dioxide as Grain Protectant and Surface Treatment Against Two Major Stored-Product Beetle Species

The insecticidal efficacy of a commercial silicon dioxide (SiO2) formulation (ChinCheX®) was evaluated as a grain protectant and surface treatment against adults of Oryzaephilus surinamensis (L.) and Tribolium confusum Jacquelin du Val. In grain-treatment bioassays, wheat and barley kernels were treated with 0, 100, 200, 500 and 1000 ppm of the SiO2 formulation and adult mortality was assessed after 3, 7, 14 and 21 d of exposure. Mortality increased with both concentration and exposure interval. Complete mortality of O. surinamensis was achieved at all concentrations, including 100 ppm after 21 d, whereas T. confusum was less susceptible at the lowest concentration but reached complete mortality at concentrations of 200 ppm or higher. Progeny production of both species was almost completely suppressed in all treated groups. In surface-treatment bioassays on concrete and plastic surfaces, high mortality (>85%) was recorded within 3 d of exposure at all application rates, while complete mortality was generally achieved within 7 d regardless of surface type. Overall, the SiO2 formulation tested exhibited strong insecticidal activity both as a grain protectant and as a surface treatment, indicating considerable potential for the management of storage beetles in stored-product protection programs.