Insecticidal effect of graphene against three stored-product beetle species on wheat

The efficacy of two formulations of graphene powders against Rhyzopertha dominica (F.), Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) was tested on wheat. The graphene formulations using two different graphene materials were tested at different concentrations, i.e. 0, 250, 500 and 1000 ppm. Adult mortality was recorded after 7, 14 and 21 days of exposure and progeny production was recorded after 65 days. Our results indicate that the increase of concentration increased adult mortality and decreased progeny production. Both graphene formulations showed similar results. Rhyzopertha dominica and S. oryzae were found to be the most susceptible species with 100% mortality after 21 days of exposure to 250 ppm. Application of 500 and 1000 ppm caused 100% mortality after 7 days of exposure. In contrast, for T. castaneum some survival was recorded after 7 days of exposure at 500 and 1000 ppm, but mortality was 100% at the 21-day exposure interval. For both formulations, progeny production was negligibly reduced at the two highest graphene concentrations. The findings of the present research showed that the graphene materials showed high efficacy, especially at 500 and 1000 ppm, and could be used to control the species tested and indicated graphene insecticidal properties most likely are based on a physical mode of action.