目的 验证EP不育剂对莫氏田鼠种群野外控制成效。方法 2004年在内蒙古锡林郭勒盟白音锡勒牧场羊草样地进行野外实验。4月底投药,采用样线跟踪调查方法对5－7月莫氏田鼠种群进行调查。数据分析采用独立性样本t检验。结果 EP不育剂对莫氏田鼠种群繁殖具有较好抑制效果,1个月后投药区莫氏田鼠的子宫损伤率达到78.9%,妊娠率下降至0;2个月后投药区莫氏田鼠的子宫损伤率依然维持在较高水平(76.7%),妊娠率和平均胎仔数开始回升,但与对照区比较差异有统计学意义;3个月后投药区雌鼠子宫损伤率开始回落到30.0%。结论 EP不育剂对莫氏田鼠的种群繁殖作用效果可以维持3个月,同时也是一种安全性的不育剂。

Objective To test the effect of a contraceptive compound (levonorgestrel-quinestrol, designated EP-1) on reproduction in field populations of Maximowicz's vole (Microtus maximowiczii). Methods In 2004, a field trial was conducted in a guinea grass plot in Baiyinxile pasture, Xilingol league, Inner Mongolia, China. EP-1 was applied at the end of April and the reproductive parameters of field voles were inspected in May to July by monthly line transect census and track surveys. Data were analyzed by independent-samples t test. Results EP-1 strongly inhibited reproduction in female voles in the field. In the EP-1 baited area, the uterine damage rate in adult female voles was 78.9% while their pregnancy rate dropped to 0% in early June. In early July, uterine damage rate remained at a similar high level (76.7%) as that in June; the corresponding pregnancy rate and mean litter size both rose rapidly, but still differed from those in the untreated control area significantly (P<0.05). In early August, the uterine damage rate in female voles fell to 30.0%. Conclusion EP-1 is a safe contraceptive compound for the effective control of reproduction in field M. maximowiczii populations. Its inhibitory effect lasts three months before the vole's reproduction starts to recover.