Burrow Dusting or Oral Vaccination Prevents Plague-Associated Prairie Dog Colony Collapse
Published online: June
Burrow Dusting or Oral Vaccination Prevents Plague- Associated Prairie Dog Colony Collapse
Daniel W. Tripp 2
Tonie E. Rocke 1
Jonathan P. Runge 0
Rachel C. Abbott 1
Michael W. Miller 2
0 Colorado Division of Parks and Wildlife, Terrestrial Resources Program , 317 West Prospect Road, Fort Collins, CO 80526-2097 , USA
1 United States Geological Survey, National Wildlife Health Center , 6006 Schroeder Road, Madison, WI 53711 , USA
2 Colorado Division of Parks and Wildlife, Wildlife Health Program , 4330 Laporte Avenue, Fort Collins, CO 80521-2153 , USA
Plague impacts prairie dogs (Cynomys spp.), the endangered black-footed ferret (Mustela nigripes) and other sensitive wildlife species. We compared efficacy of prophylactic treatments (burrow dusting with deltamethrin or oral vaccination with recombinant ''sylvatic plague vaccine'' [RCN-F1/V307]) to placebo treatment in black-tailed prairie dog (C. ludovicianus) colonies. Between 2013 and 2015, we measured prairie dog apparent survival, burrow activity and flea abundance on triplicate plots (''blocks'') receiving dust, vaccine or placebo treatment. Epizootic plague affected all three blocks but emerged asynchronously. Dust plots had fewer fleas per burrow (P < 0.0001), and prairie dogs captured on dust plots had fewer fleas (P < 0.0001) than those on vaccine or placebo plots. Burrow activity and prairie dog density declined sharply in placebo plots when epizootic plague emerged. Patterns in corresponding dust and vaccine plots were less consistent and appeared strongly influenced by timing of treatment applications relative to plague emergence. Deltamethrin or oral vaccination enhanced apparent survival within two blocks. Applying insecticide or vaccine prior to epizootic emergence blunted effects of plague on prairie dog survival and abundance, thereby preventing colony collapse. Successful plague mitigation will likely entail strategic combined uses of burrow dusting and oral vaccination within large colonies or colony complexes.
Black-tailed prairie dog; Cynomys ludovicianus; Deltamethrin; Plague; Raccoonpox; Vaccine
INTRODUCTION
Plague—caused by the bacterium Yersinia pestis—impacts
numerous wildlife species worldwide. Its introduction has
contributed to the degradation of North American grassland
and shrub-steppe ecosystems (Gage and Kosoy 2005;
Augustine et al. 2008; Eads and Biggins 2015). Prairie dogs (Cynomys
spp.) in particular suffer plague-driven mass mortality that
can collapse colony complexes over large geographic areas
(e.g., Ecke and Johnson 1952). Other associated wildlife
species, like the endangered black-footed ferret (Mustela nigripes)
that rely on prairie dogs for habitat or prey, may be directly or
indirectly affected by plague (Antolin et al. 2002; Biggins et al.
2010). The ability to mitigate plague at an ecologically
meaningful scale has thus emerged as a critical conservation
need
(Creekmore et al. 2002; Seglund and Schnurr 2010;
Biggins et al. 2010; Abbott et al. 2012)
.
Until recently, the plague management approach most
widely practiced in North America was reactive use of
insecticides to control fleas, the primary plague vector
(Seery et al. 2003; Biggins et al. 2010)
. This approach can be
effective in reducing mortality and spillover to domestic
animals and humans but does little to offset the broader
ecological impacts of epizootic plague. Since the early
2000s, attention has shifted to developing preventive plague
management approaches for prairie dog habitats via vector
control
(Hoogland et al. 2004; Biggins et al. 2010; Griebel
2012; Jachowski et al. 2012; Tripp et al. 2016)
and oral
vaccination
(Mencher et al. 2004; Rocke et al. 2010, 2014;
Abbott et al. 2012)
.
Here, we describe a field experiment designed to assess
and compare the effectiveness of annual burrow dusting or
oral vaccination in preventing plague in a black-tailed
prairie dog (C. ludovicianus) colony complex. Our study
provides insights into the benefits and limitations in field
application of two specific plague management tools:
deltamethrin dust
(Seery et al. 2003; Biggins et al. 2010; Tripp
et al. 2016)
and a raccoonpox-vectored plague vaccine
designated ‘‘sylvatic plague vaccine’’ or SPV
(Abbott et al.
2012; Rocke et al. 2014; Tripp et al. 2015)
. Our
observations also more broadly inform on developing adaptive
management strategies intended to prevent widespread,
plague-induced mortality among prairie dogs.
METHODS
This study was conducted during Aug 2012–Oct 2015 as a
collaboration of the Colorado Division of Parks and
Wildlife (CPW), the U.S. Geological Survey (USGS)
National Wildlife Health Center (NWHC) and the City of Fort
Collins. The CPW Animal Care and Use Committee
(file
number 05-2012 and 06-2013)
approved study protocols.
Field use of vaccine was approved by U.S. Department of
Agriculture’s Center for Veterinary Biologics (USDA CVB),
and an environmental assessment of vaccine use was
completed by (...truncated)