The web of L. triangularis consists of a flattened sheet, slightly arched in the centre and held in place by scaffolding thread above and below the sheet. The web lacks a retreat, with the resident spider hanging upside-down near the center of the sheet. The webs of L. triangularis in Maine resemble the webs of Pityohyphantes species (Jennings et al., 2003).
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Principal source:
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review:
Publication date: 2011-02-23
Recommended citation: Global Invasive Species Database (2024) Species profile: Linyphia triangularis. Downloaded from http://iucngisd.org/gisd/species.php?sc=1699 on 20-08-2024.
Reductions in native spider density are likely to be due to competitive displacement by L. triangularis. It exhibits aggressive behaviour including web “takeovers” towards conspecifics and congenerics (Jennings et al., 2003). Bednarski et al. (2010) found that native Frontinella communis spiders abandoned their webs when L. triangularis were added to plots and were less likely to establish webs in plots containing L. triangularis. Where L. triangularis took over webs, they evicted (or possibly consumed) F. communis, and reshaped the web to their own typical shaped webs, thereby making use of energetically valuable silk. Loss of a web comes at great fitness cost to spiders, in terms of time and calories (Venner et al., 2003 in Bednarksi et al., 2010).
The high density that L. triangularis populations reach in some habitats may mean that it reduces the amount of insect prey available for native spiders. However, sticky trap censuses found no evidence that L. triangularis reduces flying insect abundances (Houser et al., 2007 in Bednarski et al., 2010). Further work is needed to establish definitively whether competition for prey is important in Maine spider communities (Bednarski et al., 2010).
Competition and predation by L. triangularis on native sheet-line weavers and other spiders could lead to displacement of these species, and thus lead to a decline in biodiversity in invaded areas (Jennings et al., 2003).
Instead, assemblages of natural enemies (e.g., parasites, parasitoids, predators, and pathogens) may be needed for control or containment of this invasive spider (Houser et al., 2005).