Efficacy of amorphous silica dust for use against Sitophilus granarius and Rhyzopertha dominica as a grain protectant

Abstract

With the rise of insecticide resistance in common stored product insect species and fewer options for control due to increased regulatory oversight, it is imperative to explore other options for management. One option is the use of inert dusts such as diatomaceous earth (DE) or amorphous silica dust. In this study, we investigated the utility of an amorphous silica dust originally formulated for use against bed bugs, but applied here as a grain protectant for two stored products insects (Sitophilus granarius and Rhyzopertha doninica). A total of 200 g of wheat was conditioned with five concentrations of silica dust (ChinCheX Bed Bug Insecticide, 99 % amorphous silica), including: 0 (control), 100, 200, 500, and 1000 ppm. Insects were exposed continuously with condition evaluations at 7 and 14 days. Adults were then removed and the grain was kept for 65 d to assess progeny production. Mortality was 90 and 100 % for the 500 and 1000 ppm treatments for R. dominica and 100 % for both 500 and 1000 ppm treatments for S. granarius. Progeny production was less than 2 insects at 200 ppm and zero at 500 and 1000 ppm for R. dominica, while for S. granarius, there was less than 1 insect at 500 ppm and zero at 1000 ppm. Overall, we found that silica dust is an effective grain protectant on wheat against these bulk storage pests and provides a valuable option for use in an integrated pest management program.