Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae)

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Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae)

ABSTRACT

Rapid urbanisation has led several spider species to adapt to synanthropic microhabitats and establish large populations outside of their native ranges. In Ireland, the establishment and widespread distribution of the Noble false widow spider Steatoda nobilis (Araneae: Theridiidae) (Thorell, 1875) has raised questions about its impact on native spider populations across the country. Through an extensive field survey of six urban centres over an 11-month period, we sought to establish population demographics for S. nobilis and other synanthropic spiders in Ireland for the first time. We surveyed fence microhabitats for both spider abundance and diversity to determine the influence of variables such as prey availability and climate. Of the 20 identifiable species observed, S. nobilis and the missing sector orb weaver Zygiella x-notata (Clerck, 1757) typically made up more than 80% of the spider abundance regardless of location surveyed, including two new Irish counties where S. nobilis had previously not been recorded but is now well established (Co. Mayo and Co. Sligo). Our results also indicated that the diversity of synanthropic spiders is significantly affected by seasonality and prey availability, but largely unaffected by daily weather conditions.

Collier, B.L., Leonard, D., Lyons, K., Dunbar, J.P., Lawton, C. and Dugon, M.M. (2026), Survey of Synanthropic Spiders in Ireland Reveals Expansion and Dominance of the Invasive Noble False Widow Steatoda nobilis in Urban Habitats (Araneae: Theridiidae). Ecol Evol, 16: e73193. https://doi.org/10.1002/ece3.73193