Zolnik Christine P, Falco Richard C, Kolokotronis Sergios-Orestis, Daniels Thomas J
Department of Biological Sciences, Fordham University, Bronx, New York, United States of America; Vector Ecology Laboratory, Louis Calder Center-Biological Field Station, Fordham University, Armonk, New York, United States of America.
New York State Department of Health, Louis Calder Center, Armonk, New York, United States of America.
PLoS One. 2015 Oct 2;10(10):e0139473. doi: 10.1371/journal.pone.0139473. eCollection 2015.
Pathogen prevalence within blacklegged ticks (Ixodes scapularis Say, 1821) tends to vary across sites and geographic regions, but the underlying causes of this variation are not well understood. Efforts to understand the ecology of Lyme disease have led to the proposition that sites with higher host diversity will result in lower disease risk due to an increase in the abundance of inefficient reservoir species relative to the abundance of species that are highly competent reservoirs. Although the Lyme disease transmission cycle is often cited as a model for this "dilution effect hypothesis", little empirical evidence exists to support that claim. Here we tested the dilution effect hypothesis for two pathogens transmitted by the blacklegged tick along an urban-to-rural gradient in the northeastern United States using landscape fragmentation as a proxy for host biodiversity. Percent impervious surface and habitat fragment size around each site were determined to assess the effect of landscape fragmentation on nymphal blacklegged tick infection with Borrelia burgdorferi and Anaplasma phagocytophilum. Our results do not support the dilution effect hypothesis for either pathogen and are in agreement with the few studies to date that have tested this idea using either a landscape proxy or direct measures of host biodiversity.
黑腿蜱（肩突硬蜱，1821年命名）体内病原体的流行情况往往因地点和地理区域而异，但这种差异的根本原因尚不清楚。了解莱姆病生态学的努力提出了这样一种观点，即宿主多样性较高的地区由于低效宿主物种数量相对于高效宿主物种数量增加，疾病风险会降低。尽管莱姆病传播周期常被引为这种“稀释效应假说”的模型，但几乎没有实证证据支持这一说法。在此，我们以景观破碎化作为宿主生物多样性的替代指标，沿着美国东北部从城市到农村的梯度，对黑腿蜱传播的两种病原体进行了稀释效应假说测试。确定每个地点周围不透水表面的百分比和栖息地碎片大小，以评估景观破碎化对黑腿蜱若虫感染伯氏疏螺旋体和嗜吞噬细胞无形体的影响。我们的结果不支持这两种病原体的稀释效应假说，并且与迄今为止少数使用景观替代指标或宿主生物多样性直接测量方法来测试这一观点的研究结果一致。
