Rhododendron nectar - toxic?

[Kate Atchley]

Living as I do where rhododendrons are spreading - ponticum mainly - I am sometimes told that the honey from my bees must contain poisonous nectar.

Is this so? Does it vary with rhodi species? How about ponticum in particular?

In practice, I seldom see bees on ponticum - honeybees or other types of bees. But I would love to know more about this.

Kate

[gavin]

Our man on Colonsay knows more than most: http://www.colonsay.org.uk/honey6.html

G.

[Kate Atchley]

Thanks Gavin, very helpful. Anyone anything to add to Andrew Abraham's wisdom? Anyone had any nasty responses to Rhododendron in honey?
Kate

[Stromnessbees]

Hi Kate

I just realized that my post on the other thread links in with your question:

There are types of rhododendron that deliver beautiful clear honey which is be highly prized and doesn't show any toxicity. For example this one: http://en.wikipedia.org/wiki/Rhododendron_ferrugineum

Doris

It says on that site that the plant contains toxins, but there is no indication that the honey would cause any problems.

[gavin]

I have to say that I find the whole business a bit worrying. The toxins are present in the Rhododendron ponticum across large parts of Scotland, but doesn't seem to have caused health problems here. Yet, as described by Xenophon in 401BC (Lampe, KF, 1988, J. Amer Med Assn 259: 2009):

'The number of bee hives was extraordinary, and all of the soldiers that ate of the honey combs lost their senses, vomited, and were affected with purging, and none of them was able to stand upright; such as had eaten only a little were like men greatly intoxicated, and such as had eaten much were like mad men and some like persons at the point of death. They lay upon the ground, in consequence, in great numbers, as if there had been a defeat; and there was general dejection. The next day, no one of them was found dead; and they recovered their senses .... '

Is it just because we usually extract honey some time afterwards, and expose the honey to the air as we do so? What might happen were someone to eat fresh comb honey after a flow from the Rhododendrons? Do folk see a Rhododendron flow in Scotland?

G.

[gavin]

A little more:

Abdulkadir Gunduz, Suleyman Turedi, Hukum Uzun, Murat Topbas Mad honey poisoning. Amer J Emergency Medicine (2006) 24: 595-598

Grayanotoxin intoxication, which is mostly seen in the eastern Black Sea region of Turkey, stems from the “mad honey” made by bees from the rhododendron plant flowers. In low doses, this causes dizziness, hypotension, and bradycardia, and in high doses, impaired consciousness, seizures, and atrioventricular block (AVB).

This case study was designed as a series of cases of patients (6 women, 2 men) aged between 35 and 75 years. All of the patients' physical examinations revealed hypotension; 4 patients had sinus bradycardia, 3 had nodal rhythm, and 1 had complete AVB. In all patients, except for the patient with AVB, heart rate and blood pressure returned to normal limits within 2 to 6 hours. Two patients were monitored in the coronary intensive care unit. Of these 2, 1 was discharged on the second day. The other was fitted with a temporary pacemaker and was discharged on the third day. All the other patients were kept in for a 6-hour observation period and were then discharged from the ED.

To date, 58 such cases have been reported, but we saw 8 patients within 2005. It is commonly seen in the east of the Black Sea region, although cases may occur from all over the eastern Black Sea region of Turkey. So far, no cases of death have been reported, although grayanotoxin causes adverse effects on the cardiovascular and respiratory systems and is therefore of considerable importance.

[Stromnessbees]

Well, Gavin, have you thrown another gauntlet?

This just screams out for a self-trial. I'll be in Austria at the beginnning of December, when I'll give a talk about Bees Abroad at a beekeepers' convention. This should give me the opportunity to track down some of this year's Almrosenhonig (Rhododendron ferrugineum honey).

I could start by taking a small quantity at first and increase the amount if nothing happens.
Does anybody else want to try it? - It's supposed to be delicious!

As it happens, the Tyrol is also one of the strongholds of the alpine version of Amm. My visit should also give me the opportunity to renew contacts with breeders of the native bees and exchange experiences. Maybe we can even get one or two new members for this forum - after all we Tyrolians are Kelts, too: There are a lot of similarities with Scotland in culture and language, there is an ancient Tyrolian type of bagpipes and the local version of a kilt used to be called a Kittl.

Doris

[gavin]

Maybe we Celts are immune to such toxins then?! Great to hear of the ancient cultural links, I just love that stuff.

Eating Rhododendron honey in December seems safe enough. Would you be brave enough to get some fresh comb honey sent by airmail to Orkney in May and try the same experiment then?!

[Stromnessbees]

Will see how it goes.

There's of course the next SICAMM (Societas internationalis pro conservatione Apis melliferae melliferae) conference in Switzerland coming up (2012), when we could try this on a whole delegation of bekeepers from all over the place. - Better not wipe them all out, though, wouldn't be good for Amm.

Doris