Possible for a Redback spider to be in the US?

Georeynolds

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9E09D9E0-56CA-4C79-81B1-068CF6B16B52.jpeg 59EF1E76-8457-4808-B4FB-12AB6CF81E0E.jpeg This guy sure looks like pictures on the web of a redback. She was found on the plateau in east Tennessee and has a solid red stripe on her back. Thoughts?
 

dangerforceidle

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All "black widow" species can retain the red stripe on their dorsal side, it's just less common in US species than it is for L. hasselti in Australia. Australia's red back is also a "black widow" species.

In Tennessee you will find L. mactans and L. variolus.
 

Veigar

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If someone were to theoretically go to Australia, take like 5 Redback eggsacs, and then let them hatch in the wild, say, in the western US, what would happen? (I understand it'd be not good, but it'd be pretty interesting to see how they'd cope with their North American counterparts)
 

myrmecophile

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My hope is that every single one of the hatchlings would die horrible gruesome deaths.
 

NYAN

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If someone were to theoretically go to Australia, take like 5 Redback eggsacs, and then let them hatch in the wild, say, in the western US, what would happen? (I understand it'd be not good, but it'd be pretty interesting to see how they'd cope with their North American counterparts)
In southern California, it is a medeterranian climate just like southwestern Australia. If redbacks were to somehow hatch there it would be likely they would be outcompete by the native and non native animals first off, but the conditions, especially in urban areas might offer a favorable environment and a few could survive. Luckily the chances of this happening are very unlikely, not a ton of people have redbacks as they are somewhat rare still in the USA, and those who do have them are responsible I would hope and wouldn’t allow any escapes.
 
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The Snark

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(I understand it'd be not good, but it'd be pretty interesting to see how they'd cope with their North American counterparts)
I'd agree there. I've often wondered about the bridge between new world, old world, and the Lemurian and how, when and where Latro crossed it.
 

Dradicus

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Hello, much like others here, I have been brought here for research. I am visiting family in south western VA this week and happened to walk out to grab something from my truck after dark. I think spiders are awesome and I’d hate to kill them but I want to error on the safe side just in case. As I was walking out I noticed a very large web with a pretty decent sized spider in it. I went to grab a flashlight and my phone and it had retreated to a round web a little smaller than a tennis ball. They are black with red stripes on their backs. There are three different webs with three spiders and once I took the pictures I noticed the little ones. Anyone help me out here? Might have to zoom in a little.
 

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NYAN

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Hello, much like others here, I have been brought here for research. I am visiting family in south western VA this week and happened to walk out to grab something from my truck after dark. I think spiders are awesome and I’d hate to kill them but I want to error on the safe side just in case. As I was walking out I noticed a very large web with a pretty decent sized spider in it. I went to grab a flashlight and my phone and it had retreated to a round web a little smaller than a tennis ball. They are black with red stripes on their backs. There are three different webs with three spiders and once I took the pictures I noticed the little ones. Anyone help me out here? Might have to zoom in a little.
It’s a latrodectus sp. could be mactans or variolus. Quite a beautiful female, and a little bit higher up than I usually see widows. She won’t bother anyone as long as no one sticks their hands in her web. As with all widows they are shy in nature and do have a powerful venom but would rather use it on food. The ‘little spiders’ are actually old molts by the looks of it. If there are other questions or concerns please feel free to post more.
 
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Geb Arachnia Whitney

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The most powerful (LD50-mice) venom in Latros is in a North American species, L Geometricus. However, this is not the determining factor in the (very rare) need for anti-venin.
The determining factor is always the MMO, Means, Method and Opportunity. The most anti-venin ever prescribed for a patient was in fact an Australian man and a Hasselti was involved. The spider was trapped between his body and the bed and bit effectively multiple times. This is extraordinary and extraordinarily rare. The average Latro bite is usually trivial, described by one expert as a warning nip a dog would give. They will always run and hide if at all possible.

Two Latro bites. The red, recent - L Hasselti, and the bump on my knuckle - L Hesperus, 30 years old. Neither was medically significant.



LD50 values for some of the N.A. Latrodectus species:

Latrodectus geometricus = .43 mg/kg (IV) & .223 mg/kg (IP)
Latrodectus hesperus = .84 mg/kg (IV)
Latrodectus mactans = 1.39 mg/kg (IV) & .90 mg/kg (SC)
Latrodectus bishopi = 2.2 mg/kg (could be IP)
Latrodectus variolus = 1.8 mg/kg (IP)

(Data from @Widowman10 web site: https://sites.google.com/site/widowman10/)

A report I read from the Museum and Art Gallery, Northern Territory, http://www.magnt.net.au/ had the LD-50 of Hasselti at .60-.85 mg/kg. Equivalent to Hesperus.


L. Geometricus is an African species of Latrodectus. L. Hesperus actually has the lowest LD-50 out of all north American widows, southerns being right in the middle, and norterns being more toxic than both, yet, not as aggressive as a southern widow. As well, L. Geometricus should be viewed as an invasive species, as it kills of native black widows. The worship of non-native species ends. Revere that which is within your back-yard, and do not envy the foliage of your neighbors.
 

NYAN

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L. Geometricus is an African species of Latrodectus. L. Hesperus actually has the lowest LD-50 out of all north American widows, southerns being right in the middle, and norterns being more toxic than both, yet, not as aggressive as a southern widow. As well, L. Geometricus should be viewed as an invasive species, as it kills of native black widows. The worship of non-native species ends. Revere that which is within your back-yard, and do not envy the foliage of your neighbors.
My understanding is that mactans is the most potent of the North American species and bishopi/geometricus is the least. I’ve heard about geometricus being the most toxic, but they aren’t considered medically significant.
 

Geb Arachnia Whitney

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L. Variolus

"The LD-50 has been measured in mice as 1.20–2.70 mg (0.019–0.042 gr); each spider contains about 0.254 mg (0.0039 gr) of venom.[4]

Unlike for the related Latrodectus mactans, as of 2015 no antivenom was available"

L. Mactans


The LD-50 of L. mactans venom has been measured in mice as 1.39 mg/kg,[25] and separately as 1.30 mg/kg (with a confidence interval of 1.20–2.70).[26]

L. Hesperus & L. Mactans


"The mouse LD50 values for L. hesperus and L. mactans venoms were 1.64 mg/kg and 1.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both experiments, all mice in group 4 (L. hesperus or L. mactans venom + antivenom) survived (p < 0.0001)."


Venom potency has a great deal to do with how often the widow eats, for if she is malnourished her venom will be much more toxic. It is harder than all hell to find any decent articles on the LD50 of L. Hesperus without reading a bunch of fluff.
 

NYAN

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L. Variolus

"The LD-50 has been measured in mice as 1.20–2.70 mg (0.019–0.042 gr); each spider contains about 0.254 mg (0.0039 gr) of venom.[4]

Unlike for the related Latrodectus mactans, as of 2015 no antivenom was available"

L. Mactans


The LD-50 of L. mactans venom has been measured in mice as 1.39 mg/kg,[25] and separately as 1.30 mg/kg (with a confidence interval of 1.20–2.70).[26]

L. Hesperus & L. Mactans


"The mouse LD50 values for L. hesperus and L. mactans venoms were 1.64 mg/kg and 1.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both experiments, all mice in group 4 (L. hesperus or L. mactans venom + antivenom) survived (p < 0.0001)."


Venom potency has a great deal to do with how often the widow eats, for if she is malnourished her venom will be much more toxic. It is harder than all hell to find any decent articles on the LD50 of L. Hesperus without reading a bunch of fluff.

Are you copying a wikipedia article? Ive Found contradicting information from several different sources, both listing mactans to be more potent. The study you’re referencing is also around 90 years old. Do you have a source on the venom potency fluctuating with how well fed the spider is? I could see it being true. If it is, then these tests can’t be certain.

https://www.ncbi.nlm.nih.gov/m/pubmed/11407496/

The university of New Mexico lists mactans as being 0.55 also.
 
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Geb Arachnia Whitney

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Are you copying a wikipedia article? Ive Found contradicting information from several different sources, both listing mactans to be more potent. The study you’re referencing is also around 90 years old. Do you have a source on the venom potency fluctuating with how well fed the spider is? I could see it being true. If it is, then these tests can’t be certain.

https://www.ncbi.nlm.nih.gov/m/pubmed/11407496/

The university of New Mexico lists mactans as being 0.55 also.


The fluctuation of venom potency makes sense with the varied results on the LD50. I read through as many articles I could find then I averaged the numbers accordingly to that which I found. I did source the first two from Wikipedia, the third, I sourced from https://www.ncbi.nlm.nih.gov/pubmed/11407496

Furthermore, I find that many scientists provide rushed data, whereas a "hobbyist" actually studies the data in action. For instance, When I would feed my L. Variolus, I would never keep a set schedule, but I did keep the prey a constant species. On days which she had fed previously the night before, her prey would struggle for a good 15 minutes or so before paralysis kicked in. However, on days that I had not fed her a week prior, or when she had an egg sac in her web, the same adult female black field crickets would be paralyzed 5-7 minutes tops. And this occurred on multiple occasions during my experiments with her.
 

Smokehound714

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nobody even knows where brown widows originate from because they're cosmopolitan in range. they're commensals with humans and fail to thrive away from houses and irrigation.

Some believe they're african, others believe they're australasian or south-american.

The claim that they have the strongest venom is also bunk, I used to force them to bite me to prove to people they arent dangerous. the venom seems no more potent than a steatoda bite IMO. Well at least for me.
 

Geb Arachnia Whitney

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Latrodectus hesperus = .84 mg/kg(IV)
Latrodectus mactans = 1.39 mg/kg (IV) & .90 mg/kg (SC)
Latrodectus bishopi = 2.2 mg/kg (could be IP)
Latrodectus variolus = 1.8 mg/kg (IP)

I can agree with these. Fascinating that L. Variolus has the potential to be the largest of the American widows! You gave me a gold mine Mr. Snark. You get an award.
 
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