Noble false widow spider venom is more like a black widow’s than we thought

18 Jun 2020

A noble false widow spider. Image: NUI Galway Venom Systems Lab

Researchers have found that venom from the noble false widow spider, an invasive species to Ireland, is quite similar to a black widow’s venom.

Scientists from NUI Galway and the University of Liege in Belgium have dug through the genetic and venom make-up of Ireland’s most venomous spider, the noble false widow, to better understand how toxic it can be. Now, in a study published to the journal Toxins, the team said that the noble false widow produces a range of toxins that are also found in black widow venom.

Just as the majority of black widow bites are not serious, so far most of the recorded bites from false widows are mild. However, the study suggests that the noble false widow spider can deliver a more toxic bite than we once thought, which will help medical professionals recognise and treat symptoms of a false widow bite.

The noble false widow is a relative newcomer to Ireland and the UK, having spread across the world only in the last 20 years. While originally from the Canary Islands and Madeira, it has now spread to Europe, north Africa, west Asia and parts of North and South America.

In Ireland and the UK, it is now one of the most common species of spiders in and around urban habitats. Those unlucky to be bitten by a noble false widow can experience intense pain and swelling for a few days and, in some cases, can develop persistent stiffness in limbs.

No need to fear

As part of the study, the team used genetic and protein-based methods to identify the toxins responsible for these symptoms. Out of a total of 140 toxins recovered in the false widow, 111 were also found in their infamous cousins, the ‘true’ black widows. This included α-latrotoxins, the compounds known to disrupt the central nervous system of vertebrates, including humans.

“We know very little about spider venom and the way toxins act on the nervous system of animals and humans,” said Dr Michel Dugon, head of NUI Galway’s Venom Systems Lab.

“The false widow spider is a new addition to Irish ecosystems and it is here to stay. It is therefore important to learn about its ecology and the potential risks associated with its bite.”

Lead author of the study, John Dunbar, added that this discovery does not mean we need to be constantly in fear of these venomous spiders.

“In many parts of the world, even ‘true’ black widow bites rarely require medical attention,” he said. “However, this new discovery will ultimately help medical professionals to diagnose and treat severe false widow bites.”

Colm Gorey was a senior journalist with Silicon Republic