Evaluation of a systemic flea control insecticide in prairie dogs

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Epizootic outbreaks of plague caused by the bacterium Yersinia Pestis have dramatically impacted prairie dog (Cynomys sp.) populations across North America. Prairie dogs were one of the most abundant mammals in North America, but numbers have declined to the point that black-tailed prairie dogs (Cynomys ludovicianus), Gunnison’s prairie dog (Cynomys gunnisoni) and white-tailed prairie dogs (Cynomys leucurus) have been repeatedly petitioned for listing under the Endangered Species Act. The Utah prairie dog (C. parvidens) is listed as a federally threatened species. In addition, declines in prairie dog populations throughout the Great Plains and Intermountain West poses a threat to dependent species, especially the critically endangered black-footed ferret (Mustela nigripes). Plague epizootic outbreaks, which were restricted to western portions of the range of prairie dog species, have recently occurred in the eastern portion of their range. As recently as 2006, a “plague line” was recognized along the 100th meridian of longitude where sylvatic plague occurrences were mainly west of this “line”. However, recent occurrences of plague across that line suggest that plague might continue to spread east and decimate prairie dog populations. While a great deal of debate surrounds the cause and persistence of plague, flea control can stop the spread of plague epizootic outbreaks and even increase prairie dog survival under non-epizootic conditions. Currently, the most widely used prairie dog flea control pesticide is Deltamethrin, which requires 4-6 grams of powder to be injected into every burrow within a prairie dog colony. The application of Deltamethrin is extremely labor-intensive and can cost up to $40-42 per acre. In addition, Deltamethrin is not a flea-specific insecticide and kills other insects, which might impact insectivorous species like the mountain plover. Attempts also are underway to develop an oral plague vaccine; however, permitting and patent requirements likely place the field application of this product a number of years into the future, and similar to Deltamethrin, eventual application in the field might not be cost effective. We propose to investigate a newly-developed systemic flea control imidacloprid bait that could potentially reduce flea loads, increase prairie dog survival, and mitigate the risk of plague outbreaks within prairie dog colonies. This product would likely cost less than topical insecticides, has been shown to kill between 96-97.3% of fleas on treated prairie dogs, and would not impact insect communities within burrow systems (other than prairie dog ectoparasites). However, we still need to test the efficacy of this product for controlling flea abundance in the wild, application rates/methodologies, bait acceptance and how long the product depresses flea abundance. Objectives: 1. To analyze data and complete report that evaluates the effectiveness of imidacloprid oral flea control baits in reducing flea abundance and prevalence on wild prairie dogs. 2. To analyze data and complete report that evaluates the length of effect of imidacloprid oral flea control baits on depressing flea abundance and prevalence on wild prairie dogs. Additional funding is based on availability of funds.

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