Epizootic Plague in Prairie Dogs: Correlates and Control with Deltamethrin

Oral Sylvatic Plague Vaccine Does Not Adequately Protect Prairie Dogs (Cynomys spp.) for Endangered Black-Footed Ferret (Mustela nigripes) Conservation

“…The effectiveness of a single SPV dose in laboratory challenges of GPD ranged from 80% in juveniles to 60% of young adults and 0% of adults surviving Y. pestis challenge 6 months postvaccination (Rocke et al 2015 ). The substantial PD declines observed during epizootics on SPV-treated plots during this study, along with four others summarized by Biggins et al ( 2021b : Table 2 ) are not unlike the results from laboratory studies, especially when typical wild PD population age structure and age-specific protection levels, along with bait consumption rates, are considered. * While PD population indices on vaccine plots in those four studies Biggins et al ( 2021b ) declined 14% less than on placebo plots, the average declines were still substantial (69%).…”

“…The substantial PD declines observed during epizootics on SPV-treated plots during this study, along with four others summarized by Biggins et al ( 2021b : Table 2 ) are not unlike the results from laboratory studies, especially when typical wild PD population age structure and age-specific protection levels, along with bait consumption rates, are considered. * While PD population indices on vaccine plots in those four studies Biggins et al ( 2021b ) declined 14% less than on placebo plots, the average declines were still substantial (69%). On the two CMR pairs where we detected plague, survival declined from preplague detection an average of 82% on vaccine plots and 80% on placebo plots.…”

“…With a focus on comparing Rb+ PD during a year when Y. pestis was not detected, but was then detected the following year fostering the scenario where vaccine effectiveness should shine if protective, there were virtually no differences in reencounter rates between vaccine and placebo plots. All of these effect sizes are small, especially in comparison to the positive effects of flea control on PD populations during plague epizootics (Biggins et al 2021b ). Similar to results herein, Rb+ PD were reencountered at a 5% higher rate on both vaccine and placebo plots compared with Rb− PD.…”

“…The small test plots herein, and in Rocke et al ( 2017 ), Tripp et al ( 2017 ), and Boulerice ( 2017 ), would not provide sufficient habitat for BFF populations, but we believe PD survival estimates resulting from those trials are translatable to what would be expected for BFF population persistence in the face of high PD mortality. Viable BFF populations are dependent on abundant, and generally stable PD populations; thus, PD survival rates are a sensitive attribute for assessing efficacy of plague management tools (see also Biggins et al 2021b ).…”

“…If effective, SPV might increase PD survival during nonepizootic (enzootic) periods, and perhaps increase abundance during epizootic periods as well, as shown by Biggins et al ( 2010 ) and Biggins et al ( 2021b ) using flea control. Enzootic plague, as defined by Biggins and Eads ( 2019 ), likely circulates frequently in plague endemic areas, including our study area in Montana (Hanson et al 2007 , Matchett et al 2010 ).…”