Abstract：
Sika deer (Cervus nippon) are important hosts for all life stages of Haemaphysalis megaspinosa, a suspected Rickettsia vector. Because some Rickettsia are unlikely to be amplified by deer in Japan, the presence of deer may decrease the prevalence of Rickettsia infection in questing H. megaspinosa. As sika deer decrease vegetation cover and height and thereby indirectly cause changes in the abundance of other hosts, including reservoirs of Rickettsia, the prevalence of Rickettsia infection in questing ticks can also change. We investigated these possible effects of deer on the prevalence of infection with Rickettsia in questing ticks in a field experiment in which deer density was manipulated at three fenced sites: a deer enclosure (Deer-enclosed site); a deer enclosure where deer had been present until 2015 and only indirect effects remained (Indirect effect site); and a deer exclosure in place since 2004 (Deer-exclosed site). Density of questing nymphs and the prevalence of infection with Rickettsia sp. 1 in questing nymphs at each site were compared from 2018 to 2020. The nymph density at the Deer-exclosed site did not significantly differ from that at the Indirect effect site, suggesting that the deer herbivory did not affect the nymph density by reducing vegetation and increasing the abundance of other host mammals. However, the prevalence of infection with Rickettsia sp. 1 in questing nymphs was higher at the Deer-exclosed site than at the Deer-enclosed site, possibly because ticks utilized alternative hosts when deer were absent. The difference in Rickettsia sp. 1 prevalence between the Indirect effect and Deer-exclosed sites was comparable to that between the Indirect effect and Deer-enclosed sites, indicating that the indirect effects of deer were as strong as the direct effects. Examining the indirect effects of ecosystem engineers in the study of tick-borne diseases may be more important than previously recognized.
摘要：
梅花鹿（Cervusnippon）是巨大水银的所有生命阶段的重要寄主，疑似立克次体载体。因为在日本，一些立克次体不太可能被鹿放大，鹿的存在可能会降低立克次体感染的患病率。由于梅花鹿减少了植被覆盖和高度，从而间接导致其他寄主的丰度发生变化，包括立克次体的水库，立克次体感染的患病率也可以改变。我们在一项野外实验中调查了鹿对立克次体感染流行率的这些可能影响，在该实验中，在三个围栏地点操纵了鹿的密度：鹿围栏（鹿封闭地点）；直到2015年都存在鹿的鹿围栏，并且只有间接影响仍然存在（间接影响地点）；自2004年以来就进行了鹿隔离（鹿隔离地点）。询问若虫的密度和立克次体感染的患病率。从2018年到2020年，对每个地点的若虫进行了1次调查。猎鹿离闭部位的若虫密度与间接效应部位的若虫密度没有显着差异，表明鹿草食动物不会通过减少植被和增加其他寄主哺乳动物的丰度来影响若虫的密度。然而,立克次体感染的患病率。1在寻找若虫的位置比在鹿封闭的位置高，可能是因为当鹿不存在时，蜱利用替代寄主。立克次体sp的差异。1间接效应和鹿封闭位点之间的患病率与间接效应和鹿封闭位点之间的患病率相当，表明鹿的间接影响与直接影响一样强烈。检查生态系统工程师在蜱传疾病研究中的间接影响可能比以前认识到的更为重要。
