Treatment with the Immunocontraceptive Vaccine, GonaCon, Induces Temporary Fertility Control in Free-ranging Prairie Dog Populations in Colorado, USA

Authors

Aaron B. Shiels, USDA APHIS WS NWRC ColoradoFollow
Jackson Runte, Colorado State University
Emily W. Ruell, USDA APHIS WS NWRC ColoradoFollow
Douglas C. Eckery, USDA APHIS WS NWRC ColoradoFollow
Gary W. Witmer, USDA APHIS WS NWRC ColoradoFollow
Daniel J. Salkeld, Colorado State University

ORCID IDs

Shiels 0000-0002-6774-4560

Date of this Version

2024

Citation

Wildlife Research (2024) 51: WR22135

doi: 10.1071/WR22135

Handling editor: Stephanie Boyles Griffin

Comments

United States government work

Abstract

Context

Prairie dogs (Cynomys spp.) are rodents enjoyed by some humans; yet, they cause crop and property damage, and carry zoonotic disease. Non-lethal control of prairie dogs is of interest in urban/suburban settings. The injectable immunocontraceptive vaccine GonaCon (active ingredient is gonadotropin-releasing hormone [GnRH]) has been shown to be effective at reducing fertility in equine and deer, and is a US EPA-registered vaccine for use in these ungulate species.

Aims

To conduct a replicated field study to test efficacy of GonaCon in black-tailed prairie dogs (C. ludovicianus), and if found to be efficacious, to help facilitate the EPA registration of this product for prairie dog management in urban/suburban areas.

Methods

Prairie dogs were live-trapped in October–December 2018 in three treatment and three control sites. Every captured female ≥660 g was injected with 0.4 mL of either GonaCon (0.032% w/w GnRH) at treatment sites or a sham vaccine (absent of GnRH) at control sites. Juveniles and adults were counted at all six sites to establish juvenile:adult (ratio) and juvenile density in May–June 2019 (determining initial GonaCon effectiveness) and 2020 (determining persistence of contraception).

Key results

In 2019, the juvenile:adult ratio was significantly reduced (P = 0.0022) in GonaCon (mean ± s.e.: 0.23 ± 0.01) relative to the sham (1.10 ± 0.58) sites. Juvenile density was three times greater in sham than GonaCon sites. In 2020, GonaCon sites produced equal offspring to nearby sham sites.

Conclusions

GonaCon is highly effective during the first year (2019) but not in the second year (2020) if only a small area (0.6–2.8 ha) or small proportion of females in a colony is treated, such as was undertaken in this study.

Implications

In 2022, GonaCon− Prairie Dogs was EPA-registered. Treating whole colonies of prairie dogs at once is favored; yet, if small or partial colony treatment is desired, then annual GonaCon treatment may be needed.