Immunocontraceptive vaccines as fertility-control measure in the invasive raccoon

In the 1930s, the first raccoons (Procyon lotor) were released into the wild in Central Europe.After several decades, raccoons have spread throughout Europe and are identified as an invasive alien species, which forms a threat to, amongst others, the European pond sliders and many bird species.Furthermore, the raccoon spreads the raccoon roundworm, a zoonosis, and causes property damages.In Germany alone, the number of raccoons has been estimated to exceed 2 million.Attempts to manage or eradicate raccoons have mainly focused on hunting and trapping.However, due to the extreme adaptive capacity of the species and relatively high reproductive rate, the population is still growing.Hence, the development of new management tools is of crucial importance.In several species, immunocontraceptives have proven to be a valuable fertility-control tool.A number of contraceptives are available, however, their efficacy, side effects, and the effect on the population dynamic have not been tested in raccoons.Two contraceptives are especially of interest: the porcine zona pellucida (pZP) vaccine and the gonadotrophin releasing hormone (GnRH) vaccine.In a positive scenario, a single vaccination could lead to lifetime infertility.The vaccine targets females, but the territorial behaviour of males remains present, therefore an influx of new raccoons in the area is prevented.In addition, the peak in the energetic demand during the gestation and lactation will not take place, therefore decreasing the negative effect of raccoons on local fauna.