infamous black widow spiders are on the decline, and a new Study suggests that this may be due to aggressive attempts by brown widow spiders to hunt them.
The findings of this study were published in the peer-reviewed academic journal Annals of the Entomological Society of America,
Study sheds light on a web of confusion regarding the collapse of one of the most notorious types of spiders – And what could be the reasons for this.
Dangerous Wall Crawlers: What Are Black Widow Spiders?
Black widow spiders are a species of spiders within the genus ThiefAlso called “true widows”.
These spiders are relatively small, although they vary in size, and are known for two defining characteristics: their dark color and often a reddish marking in the shape of an hourglass.
The name “widow” comes from the tendency of these spiders to participate in sexual cannibalism, meaning that the female spider eats the male. Likewise, it is really only female widow spiders that pose any potential danger to humans. This is because a dose of latrotoxin will be given with the spider bite, a type of neurotoxin Which can cause pain, swelling, vomiting and muscle stiffness as part of a condition called latrodectism.
This condition often requires treatment, and without it symptoms can last for several weeks. However, despite the many fears within popular culture about black widow spiders, bites are rarely fatal and only dangerous to the elderly, very young children, pregnant people, and people with certain preexisting conditions.
Not only this, but black widows rarely bite humans, as they are known to be naturally non-aggressive towards people.
But either way, as spiders, they still play an important role in ecosystems and are located all over the world – including Israel.
However, in some places, such as the US, their numbers are declining.
Why has the number of Black Widows decreased? Enter: The Brown Widow
The problem that the black widow population is facing in some parts of America is the arrival of her close relative invasive species known as the brown widow,
Although markedly different in color, with a brownish tinge and an orange-yellow hourglass-like marking, brown widows are still close cousins of black widows, being another species of spider. Thief genus.
These spiders are also found around the world, although they are believed to have originated in South America or South Africa.
But how did they spread?
It is possible that they have been accidentally introduced into other ecosystems, possibly inadvertently aboard a cargo ship.
this is unprecedented and not many other invasive species This is how it has spread.
Due to the influx of a new player into the ecosystem, it is increasingly moving into territory currently occupied by other species, gradually working its way into becoming the dominant species in the niche.
This makes sense, with brown widows less likely to compete for food and territory with black widows.
Except that might not be the only thing at play here. Ultimately, the ecosystem in Florida, where this is partly happening, should have enough food for the two spider populations to not cause serious issues, and fewer to die of starvation than prey.
The researchers behind the study, which comes from the University of South Florida (USF), explained the evidence a bit further: Brown widows aren’t just competing with black widows, but hunting and killing them outright,
So how did he test it?
To find out, the researchers placed brown widows in observable habitat conditions alongside other species that fill the niche of cobweb spiders.
When they did so, they found that brown widows preferred to hunt and kill black widows 6.6 times more often than other species.
When brown widows were housed with red house spiders, there was a 50% chance of red house spiders living with or eating the brown widows. With triangular cobweb spiders, brown widows mated 80% of the time and were killed in only a few cases.
With black widows, however, it was flipped: brown widows killed and ate them 80% of the time.
These were for young spiders. When tested with fully grown adults, brown widows killed black widows 40% of the time, while black widows defensively killed brown widows 30% of the time.
This is surprising because of the different behavior of brown and black widows. Black widow spiders are much less aggressive and tend to avoid confrontation. However, brown widows are the opposite. In fact, they were shown to aggressively storm black widow webs to attack them.
Not only this, brown widows also reproduce very rapidly, which puts even more pressure on their black widow rivals.
Overall, it seems that brown widows may be more tolerant of spiders that are not part of their lactrodectus genus, and black widows don’t have that luxury.
How worried should humans be about this invasive new spider species?
It turns out, this may even be seen as a good thing by some.
While black widow venom does affect humans and even has a small chance of being fatal, brown widows are much less of a problem. This is because they are not able to inject the same amount of venom with their bite, so the bites are much less venomous and less problematic than those of black widows.
So maybe the Brown Widow is beneficial to us in the long run.