False widow spider found feeding on a bat for the first time

Photo courtesy of NUI Galway

Galway scientists have discovered the first case of a Noble False Widow spider feeding on a bat.

The Noble False Widow originates from Madeira and the Canary Islands and was first reported in southern England in 1879. The species has increased its range and population density in recent decades, spreading north towards Scotland, and west through Wales and Ireland.

The species has also spread globally across Europe, East Asia, North America, and South America. It now has the potential to become one of the world’s most invasive species of spider.

In parts of Ireland, the false widow has become one of the most common species of spider found near urban habitats.

It is the first time a member of this family of spiders, known as Teridiidae, has been recorded preying on a bat anywhere in the world, or any vertebrate in the UK.

It is also the first time any species of false widow spider was recorded preying on mammals.

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

The discovery was made by wildlife artist Ben Waddams at his home in North Shropsire, England.

Across two consecutive days, two Pipistrelle bats living in Mr Waddams attic were found entangled on the spider’s web below the entrance of a roost.

The first bat, a young pup, was found completely tangled in the web and discoloured from the spider feeding off its remains. The second adult bat was found alive and was released from the web.

This event is not uncommon, three years ago the Noble False Widow spider was reported feeding on a protected species of native lizard in Ireland.

Dr John Dunbar, Irish Research Council Post-Doctoral fellow, Venom Systems Lab, Ryan Institute, NUI Galway, 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.

“Even other, much smaller, species of false widows are known to capture and feed on snakes and lizards. 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.”

Over the past five years, a team led by Dr Michel Dugon in NUI Galway’s Ryan Institute, have been studying a wide range of characteristics specific to the species, including its venom, ecology, and behaviour.

Dr Dugon said that the spider is a “truly remarkable species” and that the team is “still surprised by its ability to adapt to new environments and make the most of the resources available”

The species also possesses a fast-acting neurotoxic venom, with a similar makeup to true black widows. The venom can cause muscular paralysis and allows the spiders to occasionally feed on small reptiles and mammals.

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.

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