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Flea control with FipBits to prevent plague from killing black-footed ferrets and their prairie dog prey
Randy Matchett, U.S. Fish and Wildlife Service
January 15th, 2023 
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Project Collaborators:
Project Collaborators: U.S. Fish and Wildlife Service U.S. Geological Service Arizona Game and Fish Department Prairie Wildlife Research BASF Colorado State University World Wildlife Fund Model Avionics Buffalo Gap National Grasslands Badlands National Park Smithsonian Conservation Biology Institute American Prairie Turner Endangered Species Fund |
Background
The primary biological challenge to recovery of endangered black-footed ferrets (BFFs) is sylvatic plague, caused by the bacterium Yersinia pestis, and vectored primarily by fleas. This is the same bacteria that killed some 25 million people during the Black Death in Europe from 1347-1351. Plague was introduced to North America around 1900 and is highly lethal to both BFFs and the prairie dogs (PDs) on which BFFs are obligate dependents for habitat and prey. Plague has eliminated thousands of PD colony acres in a short time at many black-footed ferret reintroduction areas, and including the site where the last wild population of BFFs was discovered in 1981 near Meeteetse Wyoming. Various insecticide dust products have been used successfully for decades in efforts to control fleas and prevent plague. Those treatments are expensive, costing around $30/acre, as the dust needs to be squirted down every single PD burrow on a colony. In addition, fleas can develop resistance to insecticides, so alternative active ingredients are desperately needed.
Fipronil is the active ingredient in Frontline spray that has been used topically on dogs and cats to control fleas and ticks for more than 25 years. Researchers began evaluating grain treated with fipronil (0.005% by weight) placed at prairie dog burrows for flea control on PDs in 2016. PDs eat the grain and the fipronil and metabolites are mostly stored in fat and slowly released into the PD’s blood stream. Adult fleas are then killed when taking a blood meal from the PD. Fipronil residues are excreted over time in PD feces and are often deposited in their underground burrow systems and nest chambers where flea eggs hatch into larvae. Flea larvae often feed on organic matter, including PD feces, and researchers have learned flea larvae are also killed when they consume feces from PDs that have eaten fipronil-treated bait. It is thought such fipronil residues in PD feces can persist for a long time underground and that may help explain the high degree of flea control observed for 1-2 years after a single treatment. Fipronil grain treatments are also expensive, costing around $30/acre, as the label calls for placing 1/2 cup of treated grain at every PD burrow.
Fipronil is the active ingredient in Frontline spray that has been used topically on dogs and cats to control fleas and ticks for more than 25 years. Researchers began evaluating grain treated with fipronil (0.005% by weight) placed at prairie dog burrows for flea control on PDs in 2016. PDs eat the grain and the fipronil and metabolites are mostly stored in fat and slowly released into the PD’s blood stream. Adult fleas are then killed when taking a blood meal from the PD. Fipronil residues are excreted over time in PD feces and are often deposited in their underground burrow systems and nest chambers where flea eggs hatch into larvae. Flea larvae often feed on organic matter, including PD feces, and researchers have learned flea larvae are also killed when they consume feces from PDs that have eaten fipronil-treated bait. It is thought such fipronil residues in PD feces can persist for a long time underground and that may help explain the high degree of flea control observed for 1-2 years after a single treatment. Fipronil grain treatments are also expensive, costing around $30/acre, as the label calls for placing 1/2 cup of treated grain at every PD burrow.
