The ricefield rat,Rattus argentiventer,is a significant pest of rice in Southeast Asia.Fertility control methods have the potential to provide safe and effective alternatives to control methods that often include indisc...The ricefield rat,Rattus argentiventer,is a significant pest of rice in Southeast Asia.Fertility control methods have the potential to provide safe and effective alternatives to control methods that often include indiscriminate use of rodenticides or electric barriers.The aim of this laboratory study was to assess uptake of bait coated with different concentrations of the contraceptive hormones,quinestrol(E)and levonorgestrel(P),delivered alone and in combination(i.e.EP-1)and determine the short-term effects on reproductive parameters of adult male and female R.argentiventer.In Experiment 1,2 concentrations of E,P,and EP-1(10,20 ppm)were fed to groups of wild-caught rats for 7 days.In females,both E and EP-1 induced uterine edema.In males,EP-1 reduced epididymis and seminal vesicle weights and lowered sperm motility.However,these responses were inconsistent due to low bait acceptance,especially with increasing concentrations.In Experiment 2,EP-1(0,20,50,100 ppm)was administered by oral gavage daily for 7 days to male R.argentiventer.There were significant reductions in epididymal and seminal vesicle weights for all oral doses of EP-1,in sperm counts for the 50 ppm dose,and in sperm motility for the 20 and 50 ppm doses compared to the control group.To select the optimum dose of EP-1,we must address the poor acceptance of contraceptive-coated baits by ricefield rats.Further research is required to improve the palatability of EP-1 and to test its uptake underfield conditions.展开更多
基金All experiments followed the guidelines of the American Society of Mammalogists(Sikes et al.2016)The protocol and procedures employed were ethically reviewed and approved by the Institute of Zoology(IOZ-IACUC-2021-093)The study was supported by the International Partnership Program of Chinese Academy of Sciences,Grant No.152111KYSB20160089.
文摘The ricefield rat,Rattus argentiventer,is a significant pest of rice in Southeast Asia.Fertility control methods have the potential to provide safe and effective alternatives to control methods that often include indiscriminate use of rodenticides or electric barriers.The aim of this laboratory study was to assess uptake of bait coated with different concentrations of the contraceptive hormones,quinestrol(E)and levonorgestrel(P),delivered alone and in combination(i.e.EP-1)and determine the short-term effects on reproductive parameters of adult male and female R.argentiventer.In Experiment 1,2 concentrations of E,P,and EP-1(10,20 ppm)were fed to groups of wild-caught rats for 7 days.In females,both E and EP-1 induced uterine edema.In males,EP-1 reduced epididymis and seminal vesicle weights and lowered sperm motility.However,these responses were inconsistent due to low bait acceptance,especially with increasing concentrations.In Experiment 2,EP-1(0,20,50,100 ppm)was administered by oral gavage daily for 7 days to male R.argentiventer.There were significant reductions in epididymal and seminal vesicle weights for all oral doses of EP-1,in sperm counts for the 50 ppm dose,and in sperm motility for the 20 and 50 ppm doses compared to the control group.To select the optimum dose of EP-1,we must address the poor acceptance of contraceptive-coated baits by ricefield rats.Further research is required to improve the palatability of EP-1 and to test its uptake underfield conditions.
