Abstract:

Herbivores aggregation is beneficial to reduce the predation risk but it can also increase the transmission and infection risk of parasites. Zhuonai Lake, located in Hoh Xil, Qinghai Province, an important calving ground of Tibetan antelope (Pantholops hodgsonii). The aggregating time of Tibetan antelope in Zhuonai Lake area is mainly concentrated from early June to July (less than 30 days).Climate factors such as temperature and humidity in this region might have an important impact on the development of parasite eggs/oocysts in the host’s feces. In this study, a microclimate observer was constructed in the calving ground of Zhuonai Lake to collect local meteorological data on June 9th, 2018. In this area, fresh feces of Tibetan antelope were collected and placed outdoors for 0, 10, 15, 20, 25, 30, 35 days, and nearly one year (300 days). We used the flotation technique to detect the development status of eggs/oocysts in different periods within 35 days and the species of surviving larvae in the feces placed outdoors for nearly one year. Our aim was to preliminarily test the development, hatching, and overwintering survival of the dominant parasite eggs/oocysts in the feces of aggregated Tibetan antelope in the Zhuonai Lake area and evaluate whether the calving ground increases the risk of gastrointestinal parasite transmission and infection in Tibetan antelope. The results showed that: (1) between June 9 and July 16, the 35 days average temperature was 5℃ and the average relative humidity was 81%. (2) During the aggregating period of Tibetan antelope in Zhuonai Lake area (less than 30 days), the dominant parasite eggs/oocysts in the feces did not develop to the infective stage (Third larvae stage). For example, dominant nematode eggs, including Trichostrongylus sp., Marshallagia sp., and Nematodirus sp., only developed to the first larvae stage within 30 days. Additionally, the sporulation rates of dominant coccidian species Eimeria pantholopensis and E. wudaoliangensis were 0, 18.9 %, 54.0 % and 0, 13.5 %, 30.4 % on the 25th days, 30th days, and 35th days, respectively. (3) Few parasite eggs survived over the winter until the next year. Only a few larvae of the Marshallagia sp. and Nematodirus sp. were found in feces which were placed for nearly one year to survive over the winter in the calving ground of Zhuonai Lake. This study suggests that the risk of gastrointestinal parasite transmission and infection was low during the aggregating period of Tibetan antelope in Zhuonai Lake area. Short-term utilization of calving ground and rapid back-migration were important behavioral strategies for Tibetan antelope to avoid increasing the risk of gastrointestinal parasitic infection. Furthermore, the climate environment such as low temperature was beneficial to the natural purification of parasites.

Key words: Tibetan antelope (Pantholops hodgsonii), Zhuonai Lake, Calving ground, Temperature and humidity, Development of parasite eggs/occysts, Infection risk

摘要：

食草动物集群有利于降低被捕食的风险，同时集群也会增加感染和传播寄生物的风险。可可西里卓乃湖地区是雌性藏羚的重要产羔地，集群时间主要集中在6月上旬至7月上旬，停留时间不足30 d。区域内温度、湿度等气候因子对其粪便中的寄生虫卵发育到感染期可能存在重要影响。本研究于2018年6月9日在卓乃湖产羔地建立微气候观测仪收集当地气象数据的同时，收集新鲜藏羚粪便在当地室外分别放置0 d、10 d、15 d、20 d、25 d、30 d、35 d和约300 d，应用漂浮法检测35 d内不同时间段虫卵发育状况和放置近一年的存活幼虫数量。初步研究了卓乃湖区域内集群藏羚粪便中的优势寄生虫卵的发育及其越冬存活，探讨藏羚产羔地是否会增加藏羚胃肠道寄生虫传播和感染的风险。结果表明：(1) 6月9日至7月14日，藏羚产羔地平均温度为5℃，平均相对湿度81%；(2) 藏羚在卓乃湖产羔地集群期间，其粪便中的优势寄生虫卵不能发育到感染期 (第三期幼虫)，如粪便中的优势线虫卵毛园属线虫 (Trichostrongylus sp.)、马歇尔属线虫 (Marshallagia sp.) 和细颈属线虫 (Nematodirus sp.) 在30 d内发育仅停留在第一期幼虫；优势种藏羚艾美耳球虫 (Eimeria pantholopensis) 和五道梁艾美耳球虫 (E.wudaoliangensis) 卵在25 d、30 d、35 d的孢子化率分别是0、18.9%、54.0%和0、13.5%、30.4%；(3) 很少有寄生虫卵能够越冬存活至第二年，在卓乃湖产羔地放置近一年的粪便中仅发现极少的马歇尔属线虫和细颈属线虫幼虫。研究认为藏羚在卓乃湖集群时发生胃肠道寄生虫传播和感染的风险较低，藏羚对产羔地的短时利用和迅速回迁是其避免增加胃肠道寄生虫病感染风险的重要行为策略，且产羔地的低温等气候环境利于对寄生虫的自然净化。

关键词: 藏羚, 可可西里卓乃湖, 产羔地, 温、湿度, 寄生虫卵发育, 感染风险回避