Noble false widow could ‘destabilise’ the ecosystem

Scientists warn that the noble false widow spider could ‘destabilise’ the ecosystem after it was recently found feeding on protected bats.

A study published by scientists from the Ryan Institute in NUI Galway found the first instance of noble false widows preying on a protected species of Pipistrelle bats in the UK.

Previous research from 2018 also found the spider feeding on a protected species of viviparous lizard in Ireland.

The noble false widow is considered a generalist feeder, meaning that it does not have specific prey beyond what it is able to kill and feed on.

“Even if the bulk of their diet is bugs, if they have the opportunity, they have the weapons to actually take down big prey comparative to them,” said Dr Michel Dugon, Head of the Venom Systems Lab at the Ryan Institute in NUI Galway.

“This is normally not part of the normal food chain in the UK or in Ireland, so when you have a new predator that comes in and has those new capabilities, that can destabilise the balance.”

The noble false widow has incredibly potent venom, it contains two thirds of the toxins of a true black widow.

The species also has a special hoisting technique, that allows them to catch prey low down in their web, and quickly lift it off of the ground.

Although they are not officially defined as invasive, Dr Dugon said that he “strongly suspects” that the species has a negative impact on native spiders.

“They essentially eat or bully away native spiders because their venom is more potent,” he said.

The noble false widow also lives longer than native spiders, up to five years compared to the one-to-two-year lifespan of most native spiders.

Noble false widows are also able to breed and lay eggs faster. One noble false widow can lay up to 200 eggs per egg sac, which they can lay once a month for nine months out of the year.

Native spiders often only lay 40 to 70 eggs, two to three times a year.

Noble false widows are also able to adapt to new environments quicker than their native counterparts, possibly due to a genetic mutation in the species.

“There is some sort of adaptive ability that we don’t really understand, but we know that in Northern Europe, they are capable of being active when it’s freezing.

“At zero degrees, they still can go about and catch prey once in a while, while native spiders will hide. When it’s hot and dry, they’re very happy and very active, and when it’s very wet, they seem to be doing just as well,” said Dr Dugon

Research to measure the noble false widows’ impact on the ecosystem could start later this year, and a definite answer on the species invasiveness could be available as early as 2023.

According to Dr Dugon, attempting to get rid of the species could end up doing more harm:

“Most people wouldn’t be able to differentiate the false widow versus many of the native species of spiders, and as a result, you would have a lot of well-meaning people that would essentially exterminate all spiders around, and that would just make them worse.”

He said that there are now too many noble false widow spiders within Ireland to effectively control the population.

“We’re well past the stage where we can just eliminate them and forget about them, now it’s the question of living with them.”

Dr Dugon said “big generalisations” about spiders should not be made because of the stories surrounding the noble false widow.

“We tend to forget that spiders eat between 400 and 600 million tons of bugs every single year around the world. A world without spiders is a world in which we wouldn’t be able to live in.

“They remain very important organisms in our ecosystem and are essential to our well-being as well.”

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