Mallis Rachael E, Rieske Lynne K
University of Kentucky, Department of Entomology, S-225 Ag North, Lexington, KY 40546-0091, USA.
Environ Entomol. 2011 Dec;40(6):1378-87. doi: 10.1603/EN10278.
Eastern hemlock [Tsuga canadensis (L.) Carrière] is a foundation species in forests of eastern North America that plays a key role in ecosystem function. It is highly susceptible to the exotic invasive hemlock woolly adelgid (Adelges tsugae Annand), which is causing widespread hemlock mortality. We surveyed the spider communities of eastern hemlock and deciduous canopies over 2 yr, collecting over 4,000 spiders from 21 families. We found that eastern hemlock canopies harbored a more abundant, rich, and diverse spider community than did deciduous canopies. Five spider families were present in our hemlock collections that were absent from the deciduous collections, including Mysmenidae, Theridiosomatidae, Mimetidae, Lycosidae, and Agelenidae. In hemlock canopies there were 4× the number of web builders, consisting primarily of the Tetragnathidae and Araneidae, than active hunters, consisting primarily of the Anyphaenidae and the Salticidae. Ours is the first in depth study of the spider community in eastern hemlock. Spider abundance in hemlock canopies suggest that they may play a role regulating herbivore populations, and could possibly affect the invasive hemlock woolly adelgid, either through direct consumption of the adelgids themselves or through interactions with classical biological control agents.
东部铁杉[加拿大铁杉（Tsuga canadensis (L.) Carrière）]是北美东部森林中的一种基础物种，在生态系统功能中起着关键作用。它极易受到外来入侵物种铁杉球蚜（Adelges tsugae Annand）的侵害，这种害虫正导致铁杉大量死亡。我们在两年时间里对东部铁杉和落叶林冠层的蜘蛛群落进行了调查，从21个科中收集了4000多只蜘蛛。我们发现，东部铁杉林冠层的蜘蛛群落比落叶林冠层的更加丰富、多样。在我们收集的铁杉样本中有五个蜘蛛科是落叶样本中没有的，包括膜蛛科、长纺蛛科、拟态蛛科、狼蛛科和漏斗蛛科。在铁杉林冠层中，结网蜘蛛（主要是园蛛科和肖蛸科）的数量是活跃猎手（主要是暗蛛科和跳蛛科）的四倍。我们的研究是对东部铁杉蜘蛛群落的首次深入研究。铁杉林冠层中的蜘蛛数量表明它们可能在调节食草动物种群方面发挥作用，并且可能通过直接捕食球蚜本身或与经典生物防治剂相互作用来影响入侵的铁杉球蚜。
