Evaluation of graphene for the control of stored product insects
Abstract: Ιn a series of bioassays, the efficacy of different formulations of graphene powders
were evaluated for the control of stored product beetle species. In a first bioassay, formulations with the same particle size but with different number of layers and oxygen groups were tested for the control of Rhyzopertha dominica (F.), Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) on wheat 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. Rhyzopertha dominica and S. oryzae were found to be the most susceptible species with 100 % mortality after 21 days of exposure to 250 ppm. Furthermore, application of 500 and 1000 ppm caused 100 % mortality after 7 days of exposure. In contrast, for T. castaneum mortality was 100 % at the 21-day exposure interval. Progeny production was reduced at the two highest graphene concentrations for all graphene formulations tested. In a second bioassay, graphene formulations with different particle sizes from those of the first bioassay but with the same number of layers and oxygen groups were evaluated. Insect species tested in this bioassay were S. oryzae and R. dominica on soft wheat and Prostephanus truncatus (Horn) on maize. These species were exposed to graphene formulations at three different concentrations (0, 100, 500 and 1000 ppm) and at four different exposure intervals (3, 7, 14 and 21 days). In addition, progeny production capacity was also evaluated. In the second bioassay, mortality ranged at low levels for all insect species tested. Results of the present work have shown that some graphene formulations are effective in controlling the specific stored product insect species and can contribute to the inclusion of graphene in stored product pest management programs, as an alternative method over the use of traditional insecticides, encouraging the production of graphene-based insecticides that can be commercialized for this purpose in the near future.