Krichbaum Kristle, Mahan Carolyn G, Steele Michael A, Turner Gregory, Hudson Peter J
The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Wildl Dis. 2010 Jan;46(1):229-35. doi: 10.7589/0090-3558-46.1.229.
There is growing evidence that populations of the northern flying squirrel (Glaucomys sabrinus) are declining in the eastern United States, perhaps due to competition with the southern flying squirrel (Glaucomys volans). Potential causes include parasite-mediated or apparent competition from the shared intestinal nematode, Strongyloides robustus, which has been shown to detrimentally affect the northern flying squirrel but not the southern flying squirrel. To investigate this hypothesis, we conducted a preliminary study on the parasite community of both flying squirrel species from sites in Pennsylvania where the two species occur sympatrically and where G. sabrinus is now considered endangered at the state level. We compared these parasite communities with those from northern flying squirrels from northern New York where the southern flying squirrel is absent. We found eight species of gastrointestinal parasites (Pterygodermatites peromysci, Lemuricola sciuri, Syphacia thompsoni, Syphacia spp., Capillaria spp., Citellinema bifurcatum, Strogyloides robustus, and an unidentifiable cestode species) in both species of flying squirrels examined for our study. The parasite-mediated competition hypothesis was partially supported. For example, in Pennsylvania, S. robustus was overdispersed in southern flying squirrels, such that a small proportion of the hosts carried a large proportion of the worm population. In addition, we found S. robustus to be present in northern flying squirrels when the species were sympatric, but not where southern flying squirrels were absent in New York. However, there was no association between S. robustus and the body condition of flying squirrels. We detected a potential parasite community interaction, as S. robustus abundance was positively associated with P. peromysci.
越来越多的证据表明，美国东部地区北方飞鼠（Glaucomys sabrinus）的种群数量正在下降，这可能是由于与南方飞鼠（Glaucomys volans）的竞争所致。潜在原因包括由共同的肠道线虫——粗壮类圆线虫（Strongyloides robustus）介导的寄生虫竞争或表观竞争，研究表明这种线虫会对北方飞鼠产生不利影响，但对南方飞鼠则无影响。为了探究这一假设，我们对宾夕法尼亚州两个飞鼠物种同域分布且北方飞鼠在该州被列为濒危物种的地点的寄生虫群落进行了初步研究。我们将这些寄生虫群落与纽约北部没有南方飞鼠的北方飞鼠的寄生虫群落进行了比较。在我们研究的两种飞鼠中，我们发现了八种胃肠道寄生虫（珀氏翼形皮蝇（Pterygodermatites peromysci）、松鼠艾美耳球虫（Lemuricola sciuri）、汤普森管状线虫（Syphacia thompsoni）、管状线虫属（Syphacia spp.）、毛细线虫属（Capillaria spp.）、双叉尾线虫（Citellinema bifurcatum）、粗壮类圆线虫和一种无法鉴定的绦虫物种）。寄生虫介导的竞争假说得到了部分支持。例如，在宾夕法尼亚州，粗壮类圆线虫在南方飞鼠中的分布呈过度分散状态，即一小部分宿主携带了大部分的线虫种群。此外，我们发现当这两个物种同域分布时，北方飞鼠体内存在粗壮类圆线虫，但在纽约没有南方飞鼠的地方则没有。然而，粗壮类圆线虫与飞鼠的身体状况之间没有关联。我们检测到一种潜在的寄生虫群落相互作用，因为粗壮类圆线虫的丰度与珀氏翼形皮蝇呈正相关。
