You know it was National bee day a couple of days ago, here is something i didn't get around to posting.
Mad honey
If bees forage on rhododendron the grayanotoxin-containing nectar would get processed in the hive to create
toxin-laced honey 8. Since grayanotoxins are known to be toxic for humans this honey would be expected to exert some adverse, or at least interesting, effects.
And that’s exactly what is seen.
The most common cause of grayanotoxin poisoning in humans is from eating honey made by bees foraging on rhododendron. Small doses cause light-headedness and hallucinations. In large doses it is overtly toxic and induces the range of symptoms described above.
In Nepal and parts of Turkey this so-called ‘mad honey’
is deliberately produced. You can buy
mad honey online … a snip at $199 for 250g
9.
As well as causing light headedness and hallucinations, mad honey is consumed – particularly in Turkey – because of its perceived
therapeutic benefits for conditions such as diabetes, bowel disorders and hypertension.
Perceived because I’m not sure there’s real evidence of benefits for any of these conditions.
Mad honey, or
deli bal in Turkish, is also thought to enhance sexual performance
10. Perhaps unsurprisingly, mad honey poisoning is most commonly observed in middle-aged men
Rhododendron, bees and toxins
Rhododendron are insect pollinated and produce large amounts of sugar-rich nectar to ‘reward’ visiting pollinators. A number of species of bees are known to pollinate rhododendron, including honey bees. Surprisingly – for an insect pollinated plant – rhododendron nectar contains high levels of
diterpines which are toxic to many different animals. These types of toxins are usually produced by plants to reduce foliar grazing.
The most important (by amount) diterpine in rhododendron nectar is
grayanotoxin.
Grayanotoxin is a neurotoxin. It works,
i.e. its toxicity is due to, interference with
voltage-gated sodium channels (VGSC) in neurones. We’ve discussed VGSC’s before in the context of
resistance of Varroa to Apistan.
Although the modes of action of apistan and grayanotoxin are different, the consequences are not. If you block neuronal activity,
stuff 3 that’s important often stops working properly – ‘stuff’ like the
heart
Symptoms of grayanotoxin poisoning include cardiovascular problems, nausea, vomiting and loss of consciousness.
But wait, there’s more. Add to that heady mix one or more of the following … blurred vision, dizziness, hypersalivation, perspiration, weakness and paresthesia
4 in the extremities and around the mouth.
In higher doses, symptoms can include loss of coordination and severe, progressive, muscular weakness. Fatalities are rare but not unknown.
These are all symptoms in humans experiencing grayanotoxin poisoning.
Great … could it possibly get worse?