Galway scientists find Noble False Widows up to 230 times more poisonous than native spiders

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False widow spider

The venom of Noble False Widow spiders is up to 230 times more potent than that of native Northern European species, new research from NUI Galway has found.

Scientists from the Ryan Institute at NUI Galway demonstrated that not only is the Noble False Widow’s venom much more poisonous, but the spider is also able to adapt its attacking behaviour for different battle scenarios.

The research team carried out the study to try to understand why the spider is so successful at spreading in towns and cities throughout the world.

They investigated the potency of the spider’s venom and compared it with the venom of some of the native species it competes with for available resources.

The findings from the study, published in the international journal Toxins, may explain why Noble False Widows can tackle a range of organisms much larger than themselves, including lizards, bats, shrews, and other spiders.

The study also found that Noble False Widows can make calculated decisions on whether to attack large or small prey depending on how much venom is left in their venom glands.

If little venom is available, they avoid facing large opponents that could injure them, and instead focus on small prey.

In a battle, the Noble False Widow does not inject its venom randomly, but instead targets the most innervated body parts of its enemy, where the neurotoxic venom is most efficient.

Overall, the Noble False Widow spider killed and ate 95% of its opponents over the course of the study.

Over the past five years, the team at the University’s Venom Systems Lab, led by Dr Michel Dugon, has been studying a wide range of characteristics specific to the species including its venom, symptoms after envenomation, ecology and behaviour.

“Over the years, we have learned a lot about the Noble false widow and its venom. This study is another important step to understand the true impact this species has on the ecosystems it invades throughout the world,” said Dr Dugon.

Dr John Dunbar, Irish Research Council Post-Doctoral fellow, Venom Systems Lab, and co-senior author of the study, described the Noble False Widow spider as a ‘truly remarkable animal’.

“At every turn this species has surprised us in its ability to become globally invasive and dominate habitats it occupies.

“The tiniest amounts of venom – about 1,000th of a raindrop – can cause medically significant symptoms in humans that are about 250,000 times larger than them. Each new study brings us closer to understanding how exactly they are achieving their success.”

Originating from Madeira and the Canary Islands, the Noble False Widow spider Steatoda nobilis has the potential to become one of the world’s most invasive species of spider.

It was first reported in southern England in 1879. In recent decades it has increased its range and population density, spreading northwards towards Scotland and westward through Wales and Ireland.

In that time the species has also spread globally across Europe, East Asia, North America, and South America.

Joint first author of the study and NUI Galway graduate, Sean Rayner, said that over the past number of years we have seen a noticeable increase in Irish populations of Noble False Widow.

“This study will help us further understand what makes them so successful and hopefully highlight their potential impact to our ecosystems.”

The team of scientists is encouraging members of the public to email them at falsewidow@nuigalway.ie to report sightings of the Noble False Widow spider.

Read the full study in Toxins here: https://www.mdpi.com/2072-6651/14/9/587