Review of issues concerning the use of reproductive inhibitors,with particular emphasis on resolving human-wildlife conflicts in North America

This manuscript provides an overview of past wildlife contraception efforts and discusses the current state of research.Two fertility control agents,an avian reproductive inhibitor containing the active ingredient nicarbazin and an immunocontraceptive vaccine,have received regulatory approval with the Environmental Protection Agency and are commercially available in the USA.OvoControl G Contraceptive Bait for Canada Geese and Ovo Control for pigeons are delivered as oral baits.An injectable immunocontraceptive vaccine(GonaCon Immunocontraceptive Vaccine)was registered with the Environmental Protection Agency for use in female white-tailed deer in September 2009.An injectable product(GonaCon Immunocontraceptive Vaccine)is registered for use in female white-tailed deer.Both products are labeled for use in urban/suburban areas where these species are overabundant.Several other compounds are currently being tested for use in wildlife in the USA,Europe,Australia and New Zealand that could have promise in the future.The development and use of reproductive inhibitors for resolving human-wildlife conflicts will depend on a number of factors,including meeting the requirements of regulatory agencies for use in the environment and on the biological and economical feasibility of their use.Use will also be dependent on health and safety issues and on public acceptance of the techniques.

Feeding of grey squirrels (Sciurus carolinensis) with the contraceptive agent DiazaCon^(TM):effect on cholesterol, hematology, and blood chemistry

Grey squirrels(Sciurus carolinensis)are an invasive species in Britain and Italy.They have replaced native red squirrels(Sciurus vulgaris)throughout most of Britain,and cause damage to trees.Currently,lethal control is used to manage grey squirrel populations in Britain,but nonlethal methods might be more acceptable to the public.One such method is contraception with 20,25-diazacholesterol dihydrochloride(DiazaCon^(TM)).DiazaCon^(TM) inhibits the conversion of desmosterol to cholesterol,resulting in increasing desmosterol concentrations and decreasing cholesterol concentrations.Because cholesterol is needed for the synthesis of steroid reproductive hormones,such as progesterone and testosterone,inhibition of cholesterol synthesis indirectly inhibits reproduction.Desmosterol is used as a marker of efficacy in laboratory studies with species that do not reproduce readily in captivity.Grey squirrels were gavaged with a DiazaCon^(TM) solution for 2 days,and then fed DiazaCon^(TM)-coated peanuts for an additional 8 days at target doses of 50 and 100 mg DiazaCon^(TM) per kg body weight.There was a significant difference in cholesterol concentrations in the treatment groups compared to the control group.Cholesterol was reduced by≥40%for 2 months in both treatment groups.There were no differences among groups with respect to blood chemistry and hematology parameters,and mean values are reported.The mean overall dose of DiazaCon^(TM) received was 29.0±1.6 and 55.3±4.3 mg/kg in the low(50 mg/kg)and high dose(100 mg/kg)groups,respectively.DiazaCon^(TM) might provide an effective,acceptable alternative to lethal control.