Plague in a colony of Gunnison's prairie dogs (Cynomys gunnisoni) despite three years of infusions of burrows with 0.05% deltamethrin to kill fleas

At Valles Caldera National Preserve in New Mexico, US, infusing Gunnison's prairie dog (Cynomys gunnisoni) burrows with an insecticide dust containing 0.05% deltamethrin killed fleas which transmit bubonic plague. The reduction in the number of fleas per prairie dog was significant and dramatic immediately after infusions, with a suggestion that the reduction persisted for as long as 12 mo. Despite the lower flea counts, however, a plague epizootic killed >95% of prairie dogs after 3 yr of infusions (once per year). More research is necessary for a better understanding of the efficacy of insecticide dusts at lowering flea counts and protecting prairie dogs from plague.