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Most venomous/toxic Naja species
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by RedGKS on February 18, 2012
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I know that N. philipinensis is the most venomous of the bunch, but how do the rest pile up?
It’s often claimed that N. nivea is second, but this is just not true. According to Brown (1973), the Cape cobra has an SC (subcutaneous) LD50 (median lethal dose) of 0.72 mg/kg (this is also the figure which is listed by Dr. Bryan Grieg Fry of the Australian Venom Research Unit at the University of Queensland). Another figure for Naja nivea was 0.81 mg/kg. Its arguably the most venomous of the "true" (Naja ssp) African cobras, but definitely not second in the world. To compare, Brown claims an SC LD50 of 0.2 mg/kg for the Philippine cobra (N. philippinensis) - which is the most toxic Naja species.
Naja oxiana (Caspian cobra, Central Asian cobra) is an highly venomous Naja species with an LD50 of 0.4 mg/kg (nearly twice as potent drop for drop as Naja nivea). A LD50 of 0.53 mg/kg was given for Naja atra (Chinese cobra) - I actually have a scan of this which you can see here (left page, top paragraph): http://i55.tinypic.com/21jvc7p.jpg
Another figure for the Chinese cobra lists the LD50 at 0.57 mg/kg. Engelmann & Obst (1981) gave a figure of 0.67 mg/kg for the Chinese cobra, which still puts it ahead of the Cape cobra. Naja naja (Indian cobra) is sort of all over the place in terms of an LD50 value. I’ve seen a range from 0.45 mg/kg to 1.0 mg/kg. Brown listed the LD50 of the Indian cobra at 0.80 mg/kg, which makes the Cape cobra slightly more venomous. I believe this to be correct based on mortality rates, which tend to be higher within Cape cobra victims.
Other Naja species’ SC LD50 values: N. nigricollis (black-necked spitting cobra) is 2 mg/kg and N. haje (Egyptian cobra) is 1.15 mg/kg.
Some I.V. LD50 values (note: IV LD50’s tend to be much lower than SC LD50’s): 0.29 mg/kg for N. atra (Chinese cobra), 0.37 mg/kg for N. kaouthia (Monocled cobra), and 0.6 mg/kg for N. melanoleuca (Forest cobra).
Another overlooked species is Naja samarensis (Samar cobra). This is the closest relative to the Philippine cobra and Wolfgang Wuster has claimed that he had heard of 1 bite which resulted in severe neurotoxicity, similar to bites seen from the Philippine cobra. The composition of its venom is one that is just seems virulently toxic. I tend to believe the island bound cobras are probably the more venomous species (ie. N. philippinensis, N. samarensis, N. sputatrix, etc), but this is just a guess.
From what we know, N. philippinensis is most venomous and second is N. oxiana, followed by N. atra.
Anyone else has some input? This could be a very nice and informative discussion.
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RE: Most venomous/toxic Naja species
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by najasuphan on February 18, 2012
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I think since the water cobras, formerly Boulengerina, were reclassified under Naja that they would be the most venomous out of all of the true cobras. If you're just using the LD50 chart to go off of then N.christyi shows as number 10 and N.annulata is number 12 on the subcutaneous list.
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RE: Most venomous/toxic Naja species
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by RedGKS on February 18, 2012
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I was going to mention the Boulengerina species, but I didn't. Yes, they are highly venomous.
SC LD50 for B. christyi is 0.12 mg/kg, while B. annulata was listed at 0.14 mg/kg. I left them out purposely. Cobra venom seems to be very stable in terms of toxicity - different studies generally get similar LD50 values.
This is not true of the genus Dendroaspis (mambas), which show a great deal of variation in toxicity from one locale to the next, even from one specimen to the next. Dendroaspis polylepis (black mamba), for example, has a range from 0.05 mg/kg (Ernst & Zug et al 1996) to 0.12 mg/kg (Brown, 1973) to 0.28 mg/kg (Spawls & Branch, 1995) to 0.32 mg/kg (Engelmann & Obst, 1981).
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RE: Most venomous/toxic Naja species
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by RedGKS on February 18, 2012
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I'm not just using the LD50 menu chart that's available online. That LD50 chart online is very basic and does not delve into major factors which may or may not effect toxicity. It also has nothing on approximate lethal doses for adult humans, LD100, venom yield of species, etc.
I'm using other sources like Brown's (1973) "Toxicology and Pharmacology of Venoms from Poisonous Snakes", L.M. Chou's (1990) "Snakes of Medical Importance (Asia-Pacific region)", and Spawls & Branch's (1995) "Dangerous Snakes of Africa: natural history, species directory, venoms, and snakebite", and various independent papers, etc.
The jury is still out on many Naja species including ones I suspect of being highly venomous similar to Naja philippinensis (Naja samarensis, Naja sputatrix, Naja sumatrana, and Naja sagittifera).
We also still don't know anything about the venom of Naja katiensis, Naja nubiae (a paper on this species claims the venom is extremely toxic to mice - check it out: http://www.ncbi.nlm.nih.gov/pubmed/21171584), Naja mandalayensis, and others.
I think it is a little to early to claim N. philippinensis is the most venomous species. As it stands right now, yes it is, followed by N. oxiana. I'm not including the water cobras here - the jury is still out on them as far as I'm concerned.
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