Abstract: Objective To analyze the number and composition of Meriones unguiculatus nest fleas in Kangbao pasture, a natural plague focus in Hebei province, China, 2016-2019, to study the changes in the number of M. unguiculatus nest fleas, and to explore a statistical method for analyzing the seasonal distribution of plague vector fleas. Methods Based on the average flea index of M. unguiculatus nest fleas in different months of 2016-2019, the seasonal distribution of the nest fleas was analyzed by the concentration degree method and circular distribution method. The Watson-Williams test was used for hypothesis testing. Results A total of 138 M. unguiculatus nests were detected, in which 35 nests (25.36%) were infested by fleas. In total, 317 fleas were collected, involving 5 species of 4 genera of 3 families. The average flea index was 2.30. Through the year, the number of fleas collected was largest in July, second largest in October, and then in September. Neopsylla bidentatiformis, Nosopsyllus laeviceps kuzenkovi, and N. abagaitui showed double peaks, while Frontopsylla luculenta and Citellophilus tesquorurn mongolicus showed a single peak. According to the concentration degree analysis, the M value was 0.5-0.7 in 2016 and 2017, >0.9 in 2018, and 0.7-0.9 in 2019. The circular distribution analysis found that there was no angular mean in 2016; there were angular means in 2017-2019, but the means were not equal (F=3 714.353, P<0.05). For 2017 and 2019, the mean angle existed, and a=115.76° (r=0.535, Z=21.007, P<0.001); the increase of the number of M. unguiculatus nest fleas peaked on April 27-28, with the peak period during February 20 to July 1. For 2018, the mean angle existed, and a=167.24° (r=0.995, Z=6.806, P<0.001); the peak point of the increase was on June 18-19, and the peak period was from June 8 to June 30. Conclusion The concentration degree method and circular distribution method show that the change in the number of M. unguiculatus nest fleas is seasonal, with the peak point at the beginning of summer and the peak period during spring and summer, which is consistent with the seasonal fluctuation curve. Both methods can be used to study the seasonal fluctuation of fleas. The concentration degree is suitable for data exploration, and the circular distribution method is suitable for determination of peak point and peak period.

Key words: Plague, Meriones unguiculatus, Nest flea, Seasonality, Concentration degree method, Circular distribution method

摘要： 目的 对2016－2019年河北省鼠疫自然疫源地康保牧场监测点长爪沙鼠巢蚤数量、组成进行分析，研究长爪沙鼠巢蚤数量变化规律，探索蚤类季节分布的分析方法，为鼠疫媒介蚤类季节性分布的研究提供统计方法。方法 根据2016－2019年不同月份长爪沙鼠巢蚤平均蚤指数，运用集中度法及圆形分布法分析巢蚤季节性分布规律，采用Watson-Williams检验进行假设检验。结果 共调查长爪沙鼠窝巢138个，染蚤窝巢35个，染蚤率为25.36%，获蚤317匹，平均蚤指数为2.30，隶属于3科4属，共计5种；全年捡蚤以7月最多，其次是10月，再次是9月，其中二齿新蚤、秃病蚤蒙冀亚种和阿巴盖新蚤均呈双峰型，光亮额蚤和方形黄鼠蚤蒙古亚种呈单峰型；利用集中度法分析，2016、2017年M值均介于0.5～0.7之间，2018年M>0.9，2019年M值介于0.7～0.9之间；圆形分布法研究发现，2016年不存在角均数，2017－2019年均存在角均数，但角均数不在同一个总体角均数（F=3 714.353，P<0.05）。2017和2019年（r=0.535，Z=21.007，P<0.001）平均角存在，a=115.76°，长爪沙鼠巢蚤数量增长的高峰时点为4月27－28日，高峰期为2月20日至7月1日；2018年（r=0.995，Z=6.806，P<0.001）平均角存在，a=167.24°，增长的高峰时点为6月18－19日，高峰期为6月8－30日。结论 集中度和圆形分布法研究发现长爪沙鼠巢蚤数量变化存在季节性，高峰时点出现在夏初，高峰期存在于春夏季，与季节消长曲线研究结论基本一致，两者均可用于蚤类季节消长规律研究，其中集中度法宜于数据的探索，圆形分布法宜于高峰时点和高峰期的研究。

关键词: 鼠疫, 长爪沙鼠, 巢蚤, 季节性, 集中度法, 圆形分布法