Noble False Widow Spider captures bats in the attic

Scientists from the Ryan Institute in NUI Galway have published the first record of a Noble False Widow spider feeding on a protected species of Pipistrelle bats in the UK.

The new study, published in the international journal Ecosphere, demonstrates that False Widow spiders continue to impact native species.

It is the first time a member of this family of spiders, called Theridiidae, has been recorded preying on a bat anywhere in the world. It's also the first time for any species of false widow spider to be recorded preying on mammals.

The unique discovery was made by wildlife artist Ben Waddams at his home in north Shropshire, England. On two days, Bats living in the attic were found entangled on the spider’s web.

The first bat, was completely immobilised with its limbs pinned tightly to its torso with silk. It was slightly shrivelled and discoloured from the spider feeding off its remains. A second, larger adult bat, was entangled in the web but was later rescued from the web and released.

Three years ago the Noble False Widow spider was reported feeding on a protected species of native lizard in Ireland.

This spider was first reported in southern England in 1879 and has increased its range and population density in recent decades, spreading northwards towards Scotland and westward through Wales and Ireland. The species has also spread globally. It has the potential to become one of the world’s most invasive species of spider.

In the last five years, the team at NUI Galway led by Dr Michel Dugon have been studying a wide range of characteristics specific to the species such as its venom, behaviour, ecology and symptoms after envenomation.

Dr Michel Dugon, Head of the Venom Systems Lab, Ryan Institute and senior author of the study, said: “We have been working on the Noble False Widow for the past five years, and have learnt a great deal about this species - yet, we are still surprised by its ability to adapt to new environments and make the most of the resources available. It is a truly remarkable species.”

Dr John Dunbar, Irish Research Council Post-Doctoral fellow, Venom Systems Lab and lead author of the study, said: “In more exotic parts of the world, scientists have been documenting such predation events by spiders on small vertebrates for many years, but we are only beginning to realise just how common these events occur. Now that this alien species has become well established in Ireland and Britain, we are witnessing such fascinating events on our very own doorstep.

“This study presents yet another example of the invasive impact by the Noble false widow spider on native species. We know they are much more competitive than native spiders, and this further confirms their impact on prey species.”

They possess a fast-acting neurotoxic venom that can cause neuromuscular paralysis in terrestrial vertebrates which allows them to feed on small reptiles and mammals.

Aiste Vitkauskaite, researcher at the Venom Systems Lab, Ryan Institute said: “In the last three years alone, we have observed two occasions of the alien Noble False Widow capturing and feeding on protected species of vertebrate animals in Ireland and Britain. As the Noble False Widow continues to expand its range and increase populations across Ireland and Britain, we should expect to observe similar predation events on small vertebrate animals by this spider, including protected species.”

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