Geographic variation of phosphine resistance in the red flour beetle, Tribolium castaneum
Phosphine resistance in the red flour beetle, Tribolium castaneum, a common grain pests, was determined for multiple sites across the U.S., with an emphasis on Kansas locations. Resistance was determined using the FAO discriminating dose bioassay at 30 ppm for weak resistance and 180 ppm for strong resistance. Two sites in Alabama showed survival greater than 90% for the weak resistance discriminating dose bioassay, and 76 and 84% survival at the strong resistance phenotype discriminating dose. For sites in Kansas, many populations were found to have 40% or higher survival in the weak bioassay, and one population had greater than 70% survival at the strong discriminating dose. Kansas populations are being revisited and many more populations will be assayed, with a focus on coastal port storage.