Brazilian Wandering Spider in Bananas – Fact or Fiction

Saturday 14th March 2015

The internet today has been thrumming with a news story about a lady from Bristol, some bananas from Tesco, and a deadly spider from Costa Rica.  But what is the truth and science behind attention grabbing headlines such as –
Deadly spider whose bite causes FOUR HOUR erection then KILLS found in Tesco bananas
Super-Deadly Brazilian Wandering Spider Found On Supermarket Bananas
Mother, daughters open bag of bananas to find ‘massive’ nest of world’s deadliest spiders
Deadly ‘Viagra’ spiders in Tesco bananas: Mother shocked to find fruit infested with hundreds of Brazilian arachnids whose bite can cause painful four-hour erections
And the original story –
Dad buys Tesco bananas infested with spiders whose bite can cause four hour erections

Q – Did this lady find a spider in a pack of bananas?
A detailed reading shows that the lady did not find a spider in a pack of bananas – all of the photos in the articles of spiders and bananas are from other sources.  While the lady says that the cocoon stated to ‘unfurl’ it is not clear what this means or why it was happening.
A – It appears that there was NO SPIDER

Q – Did this lady find a spider egg sac in a pack of bananas?
Next we will look at the black and white “massive spider cocoon”.  It does appear to be a spider egg sac, although the dark areas are a little odd, perhaps the egg sac was crushed in transport and has started to rot (which would not be surprising given its position on the banana) or perhaps the spider have already developed pigmentation and were on the point of hatching?
A – Yes, it looks like a spider egg sac was found.

Q – Is it a Brazilian wandering spider egg sac?
The egg sac in the photos is clearly fairly modest in size, the egg sac of a Brazilian wandering spider is closer to the size and shape of half a snooker ball.  This picture gives you the idea.  This is not the only problem, the bananas are from Costa Rica, but, unsurprisingly, the Brazilian wandering spider is from…..Brazil.  There are eight species of wandering spider, all in the genus Phoneutria and all found in South America.  However, the true Brazilian wandering spider is a rainforest specialist that lives in the heart of the Amazon, it is very unlikely to be found in a banana plantation, and does not live in Costa Rica.  Other species of wandering spider, including Phoneutria boliviensis do live in Costa Rica, but this is still a big spider with a much more substantive egg sac than that in the photos associated with this story.  In truth there are dozens of species of largish spider that live in trees in Costa Rica and lay their eggs in white egg sacs attached to trees – a full identification is not possible.
A – NO this is not a Brazilian wandering spider egg sac.

Q – Is the Brazilian wandering spider the most deadly spider in the world?
Brazilian wandering spider, called Phoneutria fera, is indeed very venomous.  Defining the most venomous anything is difficult, for instance should you measure potency by dose or by millilitre?  Other wandering spider species, including Phoneutria nigriventer, the probable stowaway in a Waitrose incident in 2014  are much less dangerous.  A study by Bucaretchi (2000) in coastal Brazil reviewed the case histories of 422 Phoneutria bites.  Serious symptoms were rare, only 2.3% of the victims required antivenom and there was a single death, a small child.
A – Possibly, but only the true Phoneutria fera.  Other species in the genus, also sometimes referred to as Brazilian wandering spiders, are less venomous.

Q – Does the venom of the Brazilian wandering spider cause four hour erections?
It’s called priapism and was observed in laboratory tests of Phoneutria venom on dogs, they became ill, drowsy and panting and then developed erections and ejaculated (Schenberg and Pereira-Lima 1971).  Similar effects were seen in mice and also observed in humans suffering from accidental bites, although not in all (relevant) cases.  Indeed a component of the venom is being investigated as a potential treatment for erectile dysfunction (Nunes et al. 2008).  Whether the erection lasts for four hours is a moot point, it is more likely that they would be for shorter periods or intermittent.
A – Um…YES

However, before you get any ideas, the bite of a wandering spider also produces intense unbearable pain, visual disturbances, agitation, salivation, and profuse sweating – perhaps not the most attractive bodily attributes.  In addition with some of the species there is a small risk of tachycardia, arrhythmia, and finally death.
There are lots of spiders in banana plantations, part of the ecosystem you see, very few are venomous to humans, and a tiny number will survive picking and transport into UK stores.  There are lots of false reports of Brazilian wandering spiders turning up in bananas – including this report – and very few confirmed reports.  There is a single report  of a bite in the UK from a Brazilian wandering spider, but given that the identification of Phoneutria fera (a very unlikely species) was only made from a photo I have doubts about the veracity of this record (let me know if you know better).
Spider egg-sacs, Banana stowaway moth cocoons and other invertebrate structures can be imported on bananas; in the case of egg-sacs usually without the mother being present.  Hatching spiderlings of even the biggest and most deadly spider are too small to penetrate your skin with their fangs, and being from tropical forests they will not survive in your house or garden and therefore they pose – no risk.

If you find an egg sac on your banana wash it off and eat your banana!

Paul Hetherington, Buglife Director, expressed sentiments shared by many at the UK bug conservation charity, “I have always checked my bananas and never found any, it’s very disappointing.”

On a more serious note Buglife is very concerned at the continuing failure of the mainstream media to apply basic standards to reporting to spider stories.  Not only does it make it harder for Buglife to raise the funds needed to save species such as the Horrid ground weaver from extinction, it makes life harder for the thousands of Britons suffering from serious arachnophobia.

If you have been affected by this story please contact Anxiety UK who are able to counsel and provide advice on treatment for arachnophobia.

Bucaretchi, F., C. R. Deus Reinaldo, S. Hyslop, P. R. Madureira, E. M. De Capitani, and R. J. Vieira. 2000. A clinico-epidemiological study of bites by spiders of the genus Phoneutria . Rev. Inst. Med. Trop. Sao Paulo. 42: 17–21
S Schenberg, FA Pereira-Lima 1971.Phoneutria nigriventer venom—pharmacology and biochemistry of its components. In. Wolfgang Bücherl & Eleanor E. Buckley : Venomous Animals and their Venoms. Volume III. Venomous Invertebrates. 537 pp. Academic Press, New York and London.
K.P. Nunes,a A. Costa-Gonçalves,a L.F. Lanza,a S.F. Cortes,b M.N. Cordeiro,c M. Richardson,c A.M.C. Pimenta,d R.C. Webb,e R. Leite,e and M.E. De Limad, 2008 Tx2-6 toxin of the Phoneutria nigriventer spider potentiates rat erectile function. Toxicon. 51(7): 1197–1206

Further reading: Wikipedia, entomological