Proceedings of the Vertebrate Pest Conference

Use of a contraceptive (i.e., fertility control) is attractive for rodent management where lethal control is unwanted. Although population reduction is generally unachievable with small-scale, short-term contraceptive use, reduced juvenile recruitment is achievable. The injectable immunocontraceptive vaccine GonaCon (active ingredient: gonadotropin releasing hormone [GnRH]) was registered in 2022 by the U.S. EPA for controlling fertility of female prairie dogs (Cynomys, a type of ground squirrel) in urban/suburban settings. Here we: 1) describe past research, including a replicated field study in Colorado (GonaCon treatment vs. control sites) testing efficacy of GonaCon in prairie dogs, which gave rise to the EPA registration of this product, 2) outline future research needs for prairie dog population management with GonaCon–Prairie Dogs, 3) describe the steps required to possibly register GonaCon for additional rodent species, and 4) describe the other fertility control pesticide products that are currently registered for use against rodents in the U.S. During the replicated field study in Colorado, prairie dogs were live-trapped in a portion (avg: 18.5%, range: 7-37%) of each colony’s total area. In treatment plots, every female captured ≥ 660 g was injected with 0.4 ml of GonaCon. GonaCon was highly effective in controlling female fertility during the first year (2019), as juvenile density was reduced 3×, but not in the second year (2020) following treatment. Treating whole colonies of prairie dogs is favored, yet if small or partial colony treatment is desired then annual GonaCon treatment may be needed. An amendment to the EPA label is in progress to allow treatment of both male and female prairie dogs. Due to recent interest from land and pest managers, other fertility control products and the steps required to possibly get GonaCon registered for additional rodent species are also outlined.