EP-1不育剂对黑线毛足鼠种群繁殖的影响

Effect of the contraceptive compound(EP-1)on reproduction of the Djungarian hamster(Phodopus campbelli)in the typical steppe

为检验EP-1不育剂对野外鼠类的施用效果,2004年在内蒙古锡林郭勒盟阿巴嘎旗白音图嘎800hm2草场进行了大田实验,并随后进行了逐月的夹线跟踪调查,分析了不育剂(EP-1)对黑线毛足鼠种群繁殖的效应。结果表明,EP-1不育剂对黑线毛足鼠种群繁殖的抑制效果良好,投药区与对照区相比,投药区黑线毛足鼠的子宫损伤率达到80%,平均胎仔数下降到对照区的2/3水平,妊娠率也下降到对照区的20%。但EP-1不育剂对雄鼠睾丸下降率的作用不明显。一次性投放EP-1不育剂,对黑线毛足鼠种群的繁殖作用时间可维持4个月以上,基本可实现对整个繁殖期的控制成效,这可能与黑线毛足鼠具有储藏种子的习性,储藏药饵多次进食有关。

In this study we have assessed the effect of the EP - 1 contraceptive compound （ quinestrol, 33.3% , and levonorgestrel 66. 7% ） on recruitment in a field population of the Djungarian hamster （Phodopus campbelli）. We applied the EP - 1 compound to a wheat bait at a ratio of 1：10 000, in a 800 ha pasture in Abagaqi for the month of May 2004. An adjacent pasture was used as the control site. Wheat bait was delivered by 1.25 kg per hectare. A trapping census was conducted over 3 days each month from before baiting commenced in May through to September, to assess the reproductive status of the population of Djungarian hamsters. Our analyses show that EP - 1 affects the reproductive success of the female hamsters. In the baited area, the EP - 1 affected the uterus of 80% of mature females. The uterus was enlarged and remained oedematous for more than 4 months. Compared to the control area, in the baited area, the pregnancy rate and the litter size of females were reduced to 20% and 66% respectively. EP - 1 had no effect on the proportion of males in the population with scrotal testes. Our study has shown that EP - 1 affects the fertility of female hamsters for more than d months following a single application of the compound in the field in spring. This prolonged effect may be related to the food-caching behaviour of the Djungarian hamster, We conclude that EP - 1 has the potential to control recruitment for the duration of the breeding season of the hamster.