Steatoda Capensis in Canaries

[filipchajdicka]

Hello Arachnoboards!
I found two of these friends in a cave where I'm staying tonight, and as far as I could google, I think it's Steatoda Capensis. But there is nowhere to find anything about them living on Tenerife, nor Canaries in general. Does anybody know if I'm mistaken or if they expand? After all, I just wanted to be sure its bite is not deadly or something, so I can sleep tight. Thank you!

 

[filipchajdicka]

That's all from photos I made, they now hid in their holes because of the light

 

[filipchajdicka]

I managed to take two more pictures today. By my humble guess, from head to butt it measures cca 5mm and so from front to back leg it's cca 15mm.

 

[The Snark]

To attempt to answer your questions.
Steatoda can have a medically significant bite but that would be very rare. S. Nobilis is known to have latrotoxin.
As for their presence, S Capensis is common throughout much of Africa, Steatoda are known to be metropolitan, and Tenerife hosts several million visitors each year. So your identification is probably correct. The international catalogues of animals tends to avoid listing transient species.

 

[filipchajdicka]

Thanks a lot for the exhausting answer! Now I'll continue to enjoy their presence with a bit more of knowledge.

 

[JaySteel]

Steatoda can have a medically significant bite but that would be very rare. S. Nobilis is known to have latrotoxin.

I have a keen interest in Steatoda species and have been researching them for some time. Can you provide a reference source for this claim please? As far as I'm aware the lengthy studies on the venom of Steatoda nobilis, by Dr J P Dunbar, and his team at Venom Systems and Proteomics Lab at NUI Galway’s School of Natural Sciences, has not found that latrotoxin is present in the venom of any Steatoda species. As for the bite being occasionally medically significant, I would also ask if you can provide any medical case details where this has proven to be the case? I just want to make sure that my information is up to date.

 

[The Snark]

I have a keen interest in Steatoda species and have been researching them for some time. Can you provide a reference source for this claim please?

If you have data that updates or contradicts these links could you post please? Additionally, I've read data that steatoda may be competing with L Geomtricus in displacing other Latro species world wide. I and @darkness975 among others would be interested in new studies in this regard.

Venomics Approach Reveals a High Proportion of Lactrodectus-Like Toxins in the Venom of the Noble False Widow Spider Steatoda nobilis

The noble false widow spider Steatoda nobilis originates from the Macaronesian archipelago and has expanded its range globally. Outside of its natural range, it may have a negative impact on native wildlife, and in temperate regions it lives in synanthropic ...

www.ncbi.nlm.nih.gov

New study confirms Noble False Widow spiders bites can result in hospitalization

NUI Galway study confirms that the Noble False Widow spider does have public health implications

phys.org

 

[JaySteel]

If you have data that updates or contradicts these links could you post please? Additionally, I've read data that Steatoda may be competing with L Geometricus in displacing other Latrodectus species world wide. I and @darkness975 among others would be interested in new studies in this regard.

Venomics Approach Reveals a High Proportion of Lactrodectus-Like Toxins in the Venom of the Noble False Widow Spider Steatoda nobilis

The noble false widow spider Steatoda nobilis originates from the Macaronesian archipelago and has expanded its range globally. Outside of its natural range, it may have a negative impact on native wildlife, and in temperate regions it lives in synanthropic ...

www.ncbi.nlm.nih.gov

New study confirms Noble False Widow spiders bites can result in hospitalization

NUI Galway study confirms that the Noble False Widow spider does have public health implications

phys.org

Thanks very much for taking the time to provide these links. This completely contradicts what I had previously been lead to believe. Fascinating reading for sure.

The recent adaptation of Steatoda nobilis, that has enabled this Mediterranean species to flourish in cooler and damper climates than those where it originated from, has facilitated the rapid spread of this species across the UK, and other countries. At the moment the only European countries that have become part of the expanded range of Latrodectus geometricus are Cyprus and Turkey. In these countries I have no doubt that native Latrodectus species are being displaced by Latrodectus geometricus. I visited Cyprus a couple of months ago and was shocked by how successful and widespread this species has become over there. I was also disappointed that Latrodectus tredecimguttatus and Latrodectus Dahli have dwindled significantly, to the point where I was unable to locate a single specimen during my two week stay.

I wonder if we are likely to see an adaptation of Latrodectus geometricus, similar to that of Steatoda nobilis, that will result in this invasive species being able to colonise parts of the UK in the foreseeable future?

 

[The Snark]

I wonder if we are likely to see an adaptation of Latrodectus geometricus, similar to that of Steatoda nobilis, that will result in this invasive species being able to colonise parts of the UK in the foreseeable future?

Just my guess, it's shaping up to where Geometricus is finding the ranges of other Latrodectus to be niches in the ecosystem for them to thrive. It wouldn't be surprising if Steatoda followed along the same lines. As I understand it, Geometricus has by far the fastest reproduction rate of all Latrodectus as it's leg up. If I recall correctly, one geo produced 32 viable egg sacks in less than a year. If Steatoda has a similar reproduction rate .................? Another factor is they prefer cool and damp locations, so much of Great Britain can easily be a prime target.

 

[JaySteel]

Steatoda nobilis can't compete with the number of egg-sacs that Latrodectus geometricus can produce. The egg-sacs produced by Steatoda nobilis also contain far less eggs than those of Latrodectus geometricus too. One advantage that Steatoda nobilis has is its tolerance of a wide variety of both damp and dry habitats, and its cold weather endurance. In the UK Steatoda nobilis can remain active when the temperatures are only around freezing. This species is very common in UK homes where there is very little moisture.

I was impressed by the tolerance of very hot weather by Latrodectus geometricus though. In Cyprus many of the webs that contained egg-sacs were built in locations that were exposed to the midday Mediterranean sun.

 

[The Snark]

@JaySteel We had an invasion of Geometricus here in northern Thailand. Under chairs in restaurants, under cabinets and so forth. Numerous multiple sacs typical of the species. I monitored them pretty closely over an area of about a square mile. Over the period of about a year their numbers diminished until I couldn't find any. Three or four years on and none can be found.
So why X 2. They were able to establish themselves then died off. Predation from local animals? Environment? The only guess I venture is they were unable to reproduce in outlying areas where pesticide use is less frequent. But all Latrodectus are pretty tolerant of pesticides. So our predators, sparassids and geckos overwhelmed them - sitting duck targets in their webs? Or?
The only cobweb weavers that thrive here are the pholcids. From observation, they appear to be ultimate survivalists, able to survive on a gnat or two once a month. and tolerate extreme hot and arid areas on out to cool and very damp and humid.

 

[JaySteel]

That's really interesting to read. I wonder why they failed to become fully established? It's also been quite surprising that Steatoda paykulliana have failed to become established anywhere in the UK. They turn up here fairly regularly as accidental imports hidden amidst imported fruit. Most specimens are taken into captivity, I have several myself as study subjects, but this species has never been found breeding in the wild in Britain, Some accidental arrivals to the UK have obviously been released into the wild but the climate of the UK is clearly too damp for them to become established here. I would have thought Thailand was suitable climate for Latrodectus geometricus though. AS you suggest maybe the sheer number of predators makes it difficult for them to reproduce at a fast enough rate?