Aerial dispersal ability does not drive spider success in a crop landscape. (19th June 2018) - Hogg, Brian N.
Abstract : 1. Although spiders can colonise ecosystems by air, dispersal capabilities differ among spider species. Web‐building spiders are thought to balloon at higher rates than hunting spiders. Spider success in agricultural systems may also depend on habitat preferences. Few studies have examined the success of aerially dispersing spiders in crop systems, and information about the dispersal capabilities of spiders in putative source habitats is limited. 2. Spiders were monitored in the air and on the foliage of vineyards and adjacent oak woodland in order to compare the aerial spider faunas between these disparate habitats and to determine whether highly dispersive species contributed disproportionately to the spider community in vineyards. 3. The results show that most aerially dispersing spiders in both habitats were web‐building dwarf spiders, Erigone spp. (Linyphiidae), although hunting spiders were also well represented in the air, especially in oak woodland. Most woodland spiders in the air appeared to be residents of oak woodland and probably dispersed only short distances. 4. Conversely, only a subset of the aerial spider fauna established in vineyards in high numbers. Spiders that dominated the aerial fauna were under‐represented on vineyard foliage, whereas several hunting spiders dispersed aerially at low rates but dominated vineyard spider composition. 5. These results suggest that aerial dispersal ability may allow spiders to reach crop systems, but that establishment depends on habitat preferences and/or competitive ability. Abstract : Spider composition differed between the air and foliage in vineyards, but was broadly similar between the air and foliage in adjacent oak woodland, which is a putative source habitat for vineyard spiders. In vineyards, web‐building spiders that dominated the aerial spider fauna were under‐represented in foliage, whereas several hunting spiders dominated foliage but dispersed by air at relatively low rates. Spider success in vineyards may be based less on aerial dispersal capacity than on tolerance of vineyard conditions. Oak woodland appeared to be a more benign habitat for many spiders.