RESISTANCE TO DELTAMETHRIN IN PRAIRIE DOG (CYNOMYS LUDOVICIANUS) FLEAS IN THE FIELD AND IN THE LABORATORY

Authors

David A. Eads, Colorado State UniversityFollow
Dean E. Biggins, USGS
Jonathan Bowser, USGS
Janet C. McAllister, Centers for Disease Control and Prevention
Randall L. Griebel, US Forest Service
Eddie Childers, National Park Service
Travis M. Livieri, Prairie Wildlife Research
Cristi Painter, US Forest Service
Lindsey Sterling Krank, The Humane Society of the United States
Kristy Bly, World Wildlife Fund

Date of this Version

2018

Citation

Journal of Wildlife Diseases, 54(4), 2018, pp. 745–754

Comments

© Wildlife Disease Association 2018

DOI: 10.7589/2017-10-250

Access provided by University of Nebraska at Lincoln

Abstract

Sylvatic plague poses a substantial risk to black-tailed prairie dogs (Cynomys ludovicianus) and their obligate predator, the black-footed ferret (Mustela nigripes). The effects of plague on prairie dogs and ferrets are mitigated using a deltamethrin pulicide dust that reduces the spread of plague by killing fleas, the vector for the plague bacterium. In portions of Conata Basin, Buffalo Gap National Grassland, and Badlands National Park, South Dakota, US, 0.05% deltamethrin has been infused into prairie dog burrows on an annual basis since 2005. We aimed to determine if fleas (Oropsylla hirsuta) in portions of the Conata Basin and Badlands National Park have evolved resistance to deltamethrin. We assessed flea prevalence, obtained by combing prairie dogs for fleas, as an indirect measure of resistance. Dusting was ineffective in two colonies treated with deltamethrin for .8 yr; flea prevalence rebounded within 1 mo of dusting. We used a bioassay that exposed fleas to deltamethrin to directly evaluate resistance. Fleas from colonies with .8 yr of exposure to deltamethrin exhibited survival rates that were 15% to 83% higher than fleas from sites that had never been dusted. All fleas were paralyzed or dead after 55 min. After removal from deltamethrin, 30% of fleas from the dusted colonies recovered, compared with 1% of fleas from the not-dusted sites. Thus, deltamethrin paralyzed fleas from colonies with long-term exposure to deltamethrin, but a substantial number of those fleas was resistant and recovered. Flea collections from live-trapped prairie dogs in Thunder Basin National Grassland, Wyoming, US, suggest that, in some cases, fleas might begin to develop a moderate level of resistance to deltamethrin after 5–6 yr of annual treatments. Restoration of black-footed ferrets and prairie dogs will rely on an adaptive, integrative approach to plague management, for instance involving the use of vaccines and rotating applications of insecticidal products with different active ingredients.