vicious venom | 

Calls for awareness as invasive false widow spiders on the rise in Ireland

This week a 15-week-old child was injured after being bitten multiple times in Cork

The female Noble False Widow (Pic: Dr John Dunbar, Venon Systems Lab, NUI Galway

Neil FetherstonhaughSunday World

New research has revealed how false widow spiders are up to 230 times more poisonous than domestic Irish species, which helps explain how it tackles much larger creatures including other spiders, lizards and even bats.

The rapid spread of the spider throughout Ireland is revealed in the study conducted by scientists at the Ryan Institute in NUI Galway that found how its venom is far more potent than any common northern European spider.

It can also adapt its attacking behaviour to prevail in different “battle scenarios” in which it can make "calculated decisions" on whether to attack prey of different sizes depending on how much venom it has left.

According to the findings that are published in the international journal Toxins, the false widow, or steatoda nobilis, which is originally from Madeira and the Canary Islands, has spread rapidly in Ireland in recent years.

The NUI team, led by Dr Michel Dugon, studied a wide range of its characteristics, including venom, bite symptoms, ecology and behaviour over the past five years.

During the study, experts saw how the spider killed and ate 95 per cent of its opponents.

“The venom of the false widow kills at much smaller doses,” said Dr Dugon. “Essentially they have a chemical arsenal that is a lot stronger than native spiders. That gives them a competitive advantage because they are more toxic.

"So they can kill more prey using less venom and that means that they don’t have to spend as much time and as much energy to try and produce venom.

“We think, but we haven’t quantified it yet, that the noble false widow has a negative impact on native species by actually bullying them away from their native environment,” said Dr Dugon.

Dr John Dunbar, of the Ryan Institute’s Venom Systems Lab, a co-senior author of the study, said the spider has continued to surprise scientists as to its ability to become globally invasive.

“The tiniest amounts of venom, about a thousandth of a raindrop, can cause medically significant symptoms in humans that are about 250,000 times larger than them,” he said.

“Each new study brings us closer to understanding how exactly they are achieving their success.”

Its bite usually has a similar effect on humans as a bee sting but can often lead to more serious injury, sometimes requiring hospital treatment.

Just this week, a Cork mother called for greater public awareness of the spider after her 15-week-old son was bitten multiple times.

Sarah-Jane Dennehy revealed how baby Charlie was bitten last Monday at his home in Shanagarry.

"Charlie was playing on his mat and then he was the colour purple as he screamed hysterically like I'd never heard him before," Ms Dennehy told RTE News

"I took off his trousers and saw that his left leg, from his knee to his ankle, was bright red and he had three big welts. Then I stripped off his top and as I did so a big Noble False Widow crawled out from behind his ear."

Even though Charlie was prescribed painkillers the pain didn't ease and he was taken to the emergency department where he was given more painkillers.

However, the effects of the venom only wore off after about 11 hours.

"It was really harrowing experience for Charlie and myself. I hope nobody else goes through this. Although Charlie received great medical care from his GP and the hospital, the guidelines just aren't there to deal with False Widow bites at the moment," she said.

Originating from Madeira and the Canary Islands, the Noble False Widow spider was first reported in southern England in 1879 and in recent decades has increased its range and population density.

It has since spread northwards towards Scotland and westward through Wales and Ireland while also reaching across Europe, East Asia, North America, and South America.

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