[Correlative factors related to the density of Meriones unguiculatus in the Meriones unguiculatus plague foci of Hebei province, 2001-2013].

Objective To explore the yearly, monthly and habitat-related distribution and their relations with Meriones unguiculatus density in the Hebei Meriones unguiculatus plague foci, from 2001 to 2013. Methods Data related to Meriones unguiculatus was gathered through the monitoring programs set up at the national and provincial Meriones unguiculatus plague foci in Hebei province, from 2001 to 2013. According to the yearly density of Meriones unguiculatus, criteria set for the three groups under study, were as follows:'high-risk group'—when the rodent density was≥1.00 under rodents/hm2,'warning group'—when the rodents/hm2>rodent density> 0.20,'standard group'—when rodents/hm2 rodent density≤0.20 rodents/hm2. Differences of habitats and monthly distribution among the three groups were compared, under the Kruskal-Wallis H rank sum test while their relations were under the multiple correspondence analysis. Results The Meriones unguiculatus densities were higher than 1.00 rodents/hm2, far above the set national standards, in the monitoring area, between 2001 and 2005. From 2005, though the rodent densities began to decrease, however, figures from 2008 to 2013 were still among 0.20 to 1.00 rodents/hm2. The distribution of habitats in the three groups showed that the Meriones unguiculatus densities were all different in habitats and the difference was statistically significant (P<0.05). The highest median densities were all in the arable land, with maximum value of high-risk group appeared the highest (20.50 rodents/hm2) in the wasteland. Monthly distribution showed that the Meriones unguiculatus densities were different and the difference was statistically significant (P<0.05) in the high-risk and standard groups but not statistically significant in the warning group. Data from the multiple correspondence analysis showed that there was a strong aggregation among wasteland, in April and June, while the warning group was associated with weather in July and the arable land. Conclusions When the density became higher than 1.00 rodents/hm2, the risk on animal plague increased in Hebei Meriones unguiculatus plague foci. Based on the distribution of Meriones unguiculatus, programs should be set to monitor the rodent in arable land and wasteland, in April and June, to reduce the prevalence of animals plague. Key words: Meriones unguiculatus; Rodent density; Habitats distribution; Seasonal distribution; Multiple correspondence analysis