Bowman Ruric O, Smith Robert F
Department of Biology, Lycoming College, Williamsport, PA 17814, USA.
Department of Biology, University of Mississippi, 504 Shoemaker Hall, Oxford, MS 38677, USA.
Insects. 2021 Aug 27;12(9):770. doi: 10.3390/insects12090770.
Stream insects are essential components of aquatic and terrestrial ecosystem structure and function. Terrestrial stages are important components of terrestrial food webs, and flight-capable individuals are responsible for long-distance dispersal. Horizontal migrations by flying or crawling adults away from stream channels that link insects to riparian food webs and movements across catchment boundaries are well established through empirical research, but studies examining vertical migration of adult stream insects into forest canopies are generally lacking. This study focused on differences in adult Plecoptera and Trichoptera abundance at ground level versus the riparian canopy and differences in abundances among summer and autumn sampling periods to empirically demonstrate use of canopy ecosystems by stream insects. Malaise traps at ground level and canopy traps placed 8 to 10 m above the stream at four sites in the Mosquito Creek watershed (Pennsylvania) were used to examine vertical migration. Larval assemblages were collected and compared to adult assemblage to investigate patterns of local migration in the catchment. We found significantly more stream insects at ground level than in the forest canopy for Trichoptera, Plecoptera, and all individual plecopteran families, but a meaningful number of individuals were found in the riparian canopy. Canopy abundances were similar to abundances captured in adjacent ground-level habitats in other studies. Comparisons of adult and larval abundances among sites, taxa, and stages indicated site- and taxon-specific patterns for vertical movement into riparian canopies. Demonstrating that adult stream insects utilize riparian forest canopies indicates that riparian forest conservation should be prioritized over reforestation and that several potential research questions exist to inform riparian management.
溪流昆虫是水生和陆地生态系统结构与功能的重要组成部分。陆地阶段是陆地食物网的重要组成部分，具有飞行能力的个体负责长距离扩散。通过实证研究，成年昆虫通过飞行或爬行离开溪流渠道进行水平迁移，将昆虫与河岸食物网联系起来，以及跨越集水区边界的移动已得到充分证实，但研究成年溪流昆虫垂直迁移到森林冠层的研究普遍缺乏。本研究聚焦于成年襀翅目和毛翅目昆虫在地面与河岸冠层的丰度差异，以及夏季和秋季采样期之间的丰度差异，以实证证明溪流昆虫对冠层生态系统的利用。在宾夕法尼亚州蚊子溪流域的四个地点，使用地面的马氏网诱捕器和放置在溪流上方8至10米处的冠层诱捕器来研究垂直迁移。收集幼虫群落并与成虫群落进行比较，以调查集水区内的局部迁移模式。我们发现，对于毛翅目、襀翅目以及所有襀翅目科的单个昆虫而言，地面上的溪流昆虫明显多于森林冠层，但在河岸冠层中也发现了相当数量的个体。在其他研究中，冠层丰度与相邻地面栖息地捕获的丰度相似。对不同地点、分类群和阶段的成虫和幼虫丰度进行比较，表明进入河岸冠层的垂直移动存在特定地点和分类群的模式。证明成年溪流昆虫利用河岸森林冠层表明，河岸森林保护应优先于重新造林，并且存在几个潜在的研究问题可为河岸管理提供信息。
