One of the world’s most invasive spiders with a “potentially sinister bite” known to cause serious infections — some resistant to antibiotics — has officially established a population in New Zealand, an evolutionary ecologist says.
The noble false widow spider or Steatoda nobilis — named for its resemblance to the notorious black widow — had its first confirmed sighting in Porirua late last year.
Massey University evolutionary ecologist Steven Trewick led the efforts to confirm the identity of the spider by comparing its physical features and analysing DNA of the Porirua sample.
Since the initial sighting, the noble false widow spider had been confirmed in Christchurch, Nelson, Northland and Waikato.
Trewick said the species was already thriving in Kiwi backyards, favouring gardens, fences, outdoor furniture, and the undersides of plant pots and tarpaulins.
“Although considered less dangerous than black widows, the venom of Steatoda nobilis contains similar toxins.”
He said of particular concern was its venom’s association with antibiotic-resistant bacteria.
“Infections resulting from bites don’t always respond to treatment, and that’s a significant medical concern.”
The spider was not aggressive but would bite defensively.
Mild symptoms included swelling, redness and pain; however, some cases had been linked to more serious symptoms like tissue necrosis, nausea, hypotension, impaired mobility and secondary bacterial infections that may be resistant to standard antibiotics.
Trewick said humans often facilitated the spread of invasive species but not all environments allowed them to flourish.
“Climate conditions play a big role for cold-blooded creatures like spiders, but as we’ve found out, the noble false widow has found New Zealand’s cities quite comfortable.”
It remained to be seen how the spider would impact native wildlife but the arrival reflected broader global trends, Trewick said.
“This is part of a wider pattern of biodiversity loss and rapid environmental change. Invasive species like this one highlight how globalisation and climate shifts are reshaping our ecosystems, often at the expense of native wildlife.”
