Institute of Pathogens and Vectors, Yunnan Provincial Key Laboratory for Zoonosis Control and Prevention, Dali University, Dali, Yunnan, 671000, China.
Trop Biomed. 2021 Mar 1;38(1):111-121. doi: 10.47665/tb.38.1.020.
Chigger mites is a group of arthropods and some of them are vectors of scrub typhus. As a common synanthropic rodent species, the Brown rat (Rattus norvegicus) often harbors lots of ectoparasites including chigger mites. According to some "data mining" strategies, the present study took the advantage of the abundant original data from a long-term field ecological investigation between 2001 and 2015 to make a detailed analysis of chigger mites on R. norvegicus in Yunnan Province, Southwest of China. From 18 of 33 investigated counties, only 1414 chigger mites were collected from 1113 Brown rats with relatively low infestations. The 1414 individual chigger mites were identified as comprising 61 species, 11 genera and 2 subfamilies of the family Trombiculidae with a high species diversity (S=61, H'=3.13). Of 61 mite species, there were four main species, Walchia ewingi, Ascoschoengastia indica, W. koi and A. rattinorvegici, which accounted for 44.41% of the total mites. All the chigger mites were of aggregated distribution among different individuals of R. norvegicus. The Brown rats in the outdoor habitats harbored much more individuals and species of chigger mites with a higher mean abundance (MA=1.46) and mean intensity (MI=12.53) than in the indoor habitats (P<0.05). The overall infestation of the rats was significantly higher in the mountainous landscapes than in the flatland landscapes (P<0.001). The species similarity (C) of the mites on the male and female rats reached 64.44% with sex biased infestations. The male rats harbored more species and individuals of the mites than the female rats. The adult rats harbored more species and individuals of the mites than the juvenile rats. The species abundance distribution of the mites was successfully fitted by Preston's lognormal model with ŝ(R)=15e (α=0.31, R=0.95). On the basis of fitting the theoretical curve by Preston's model, the total mite species on R. norvegicus was estimated to be 86 species, and 25 rare mite species were missed in the sampling field investigation. The curve tendency of the species-plot relationship indicates that R. norvegicus have a great potential to harbor many species of chigger mites, and more species of the mites would be collected if more rats are sampled.
恙螨是节肢动物的一个群组，有些恙螨是恙虫病的传播媒介。作为一种常见的共生鼠种，褐家鼠（Rattus norvegicus）常携带大量的外寄生虫，包括恙螨。根据一些“数据挖掘”策略，本研究利用 2001 年至 2015 年期间长期野外生态调查的丰富原始数据，对中国西南部云南省褐家鼠上的恙螨进行了详细分析。在所调查的 33 个县中，仅从 1113 只褐家鼠中采集到了相对较低感染率的 1414 只恙螨。这 1414 只恙螨个体被鉴定为包含恙螨科 2 亚科 11 属 61 种，具有较高的物种多样性（S=61，H'=3.13）。在 61 种螨中，有四个主要种，即 Walchia ewingi、Ascoschoengastia indica、W. koi 和 A. rattinorvegici，占总螨数的 44.41%。所有恙螨在不同褐家鼠个体之间呈聚集分布。户外生境中的褐家鼠携带的恙螨个体和种类更多，平均丰度（MA=1.46）和平均强度（MI=12.53）均高于室内生境（P<0.05）。山区景观中大鼠的整体感染率明显高于平原景观（P<0.001）。雌雄鼠螨的物种相似性（C）达到 64.44%，且存在偏性感染。雄性大鼠携带的螨种和个体数量多于雌性大鼠。成年大鼠携带的螨种和个体数量多于幼年大鼠。恙螨的物种丰度分布成功地符合 Preston 的对数正态模型，ŝ(R)=15e (α=0.31, R=0.95)。根据 Preston 模型拟合理论曲线，估计褐家鼠上的总螨种数为 86 种，在野外抽样调查中遗漏了 25 种稀有螨种。物种-样方关系曲线趋势表明，褐家鼠有很大的潜力携带许多种类的恙螨，如果对更多的大鼠进行采样，将会收集到更多的螨种。
