are rhododendrons poisonous to bees

Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. Not all plants are safe for all pollinators. These are highly oxygentated diterpenoids that have been presumed to be produced elsewhere in the plant as a natural chemical defence against insects. The rhododendron family of plants includes more than 700 species, but only a handful contain grayanotoxins: Rhododendron ponticum and Rhododendron luteum.Both are common in the rugged areas around the Black Sea. I am now convinced that it is killing them and much as it pains me to, I am going to eraditcate it as I feel that, sadlt, bees need all the help they can get these days ! It seems that European rhododendrons have been poisoning honey bees as a favour to bumblebees. The common rhododendron, Rhododendron ponticum, certainly does produce toxic nectar. I have not heard anything about these trees to be honest, but will ask the question on the British Beekeepers Facebook page to see if anyone else knows and can help you. Whole Plant Traits: Plant Type: Poisonous A bee-friendly garden is a great way to support the population of these pollinators, which is dangerously declining.Did you know that not all flowers are good for bees though? I heard that some people have started to raise their bees on Cannabis flowers. Throughout the morning, the more energetic and house-proud bees actually drag the corpses away from the entrance so, without really studying the colonies at the right time, you’d never see the dead bees. It is also common to relatives of rhododendron, such as other members of the azalea, or Ericacae, family. I have heard that honey made from poison oak is delicious. This usually occurs in dense populations of these plants, particularly in the Mediterranean region. Hi Lindy, so I asked on the British Beekeepers Facebook group and have had a helpful reply already from a beekeeper called Andy Willis. | Bad Beekeeping Blog. A number of species of bees are known to pollinate rhododendron, including honey bees. Spectacular and beautiful, not many people know the common rhododendron hides a poisonous secret – its nectar is toxic to bees. Change ), You are commenting using your Twitter account. That is very kind of you to say Miksha. sempervirens. Summer Titi – Cyrilla racemiflora – is toxic to honey bees and can cause the condition called “purple brood”. (How do you find the time!?). Honey bees are attracted to all of them, toxic or non-toxic and produce a tasty honey that in spring beekeepers usually leave it in the hive, for them, to feed themselves after a long winter. Rhododendron ponticum is an invasive species and this study demonstrated that rhododendron toxins are poisonous to honeybees and mining bees. Whole Plant Traits: Plant Type: Poisonous Shrub Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. And ultimately, we may also have a good, delicious, healthy and non-toxic honey. The Poisonous Plant Guide is constructed to enable location of a plant by either knowing the common or botanical name of the plant. It had not occurred to me that non-honey bees (bumblebee ssp) may have evolved to handle the poison. Do the cannabis flowers also produce ‘mad honey’? A market for the honey exists because some people believe it improves sexual performance – this can go very wrong! When bees make honey in these fields, no other nectars get … In the foyer of the school where the event takes place there are people who have products and plants to sell specifically of interest to beekeepers. In general rhododendrons are not a preferred forage for honey bees when there are other attractive floral resources in the surroundings. So, the flower’s strategy is to avoid over-dependence on a bee that might not be faithful. Rhododendron ponticum By First Light at English Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6644210. There are actually flowers harmful to bees. ( Log Out /  - 3 ft. 0 in. When I got home late that night I looked up in Wkipedia information about my trees. It can poison many species, from humans to horses, birds and insects that ingest it. Nectar of some species of Rhododendrons has been shown to contain a toxic natural compound called grayanotoxin. There are a high number that have their proboscis extended which I have read is an indicator of pesticide poisoning (could it be the same for nectar poisoning?) Bees are drawn to the large colorful (and sweet) flowers of rhododendrons and they use the grayanotoxin rich pollen and nectar to make honey. Not all rhododendron honey is toxic, as not all rhododendron contains toxic compounds. Even though it likes … I have a bush of this type which I knew nothing about until about a week ago when I started finding dead bumblebees near it ! I was dumbfounded to read that the nectar and the pollen of these Calfornian Chesnut trees are fatally poisonous to European and Asian honey bees. The effects rarely prove fatal to humans but probably would have halted or slowed down armies for a while. - 3 ft. 0 in. 2 http://en.wikipedia.org/wiki/Rhododendron Some species are poisonous to grazing animals. Attracting bees, wild birds, insects and other pollinators to the garden seems to be a priority for gardeners these days, but it can be complicated. Hi Mel, sorry to hear that. Rhododendron Species: alabamense Country Or Region Of Origin: Alabama and Georgia Wildlife Value: Tolerates damage by rabbits. Boat Meadow, I had the same qualms. And prolific! Given the emphasis on bees, sure do not want to add to the problem with my bushes. Will let you know if I get any more replies . Its poisonous nature must act as a further discouragement. Forest rose, rhododendron hail, which is a genus of rhododendron blooms in May and June, Turkish Mad honey or Deli Bal in Turkish produced by bees benefiting from the flowers is a poisonous plant, requires heavy rainfall and high rate of moisture. Some rhododendrons are good for bees, but others have poisonous nectar. Enter your email address to subscribe to this blog and receive notifications of new posts by email. Without the coreflex I don’t think we’d notice the problem and just assume normal end-of-season population drop. while they scarfed up Rhododendron Honey and Amanita Stew." Ask an Expert is made up of groups and individual experts. If we only have hybrid rhododendron species nearby, the hybrids are likely to be less toxic too. The deaths start slowly (tens, not hundreds), build in number of deaths and colonies affected, go away, come back and the whole drama takes about a month to finish doing its damage. Rhododendron Family: Ericaceae Life Cycle: Woody Country Or Region Of Origin: USA, NC, Asia Distribution: Throughout Wildlife Value: Flowers attract humingbirds. Mad honey is produced by bees that ingest the nectar of Rhododendron ponticum and other poisonous plants that grow in Japan, Nepal, Brazil, parts of North America, Europe, and the eastern Black Sea region of Turkey. He reimbursed me half the money and told me to destroy the trees. Toxic Honey Plants Rhododendrons. Learn how your comment data is processed. Pingback: Some plants are bad for bees – The Wildlife Garden. That is so perplexing and must be very upsetting to see . The bumblebees tolerate the toxin and pollinate the flowers. You might have heard that rhododendron is a toxic plant. I found a list of other plants at http://www.buzzaboutbees.net/Plants-Toxic-for-Bees.html – scroll down to the blue ‘List Of Plants Toxic For Bees’ chart – perhaps you could check whether any of these grow near you. Insects, Diseases, and Other Plant Problems: Rhododendrons are susceptible to insect and disease problems. ( Log Out /  In Turkey, not only do the poisonous rhododendrons abound, but the humid, mountainous slopes around the Black Sea provide the perfect habitat for these flowers to grow in monocrop-like swaths. I’m bookmarking it and will have to study it. Horses and cats, like dogs, are susceptible to the poisonous effects of grayantoxin. If a bee hive incorporates a few ornamental azaleas into the honey, this is not too dangerous, but in regions where rhododendrons dominate and all come into bloom at once, the resultant honey can be extremely dangerous. It may come as a surprise that many plant materials are poisonous or toxic to honey bees.. In Turkey, not only do the poisonous rhododendrons abound, but the humid, mountainous slopes around the Black Sea provide the perfect habitat for these flowers to grow in monocrop-like swaths. The honey thus collected by the Gurung owes its inebriating properties to the nectar which the giant bees gather from a deep red-flowered species of Rhododendron, which, in turn, owes its toxicity to the compound grayanotoxin, widespread in the plant family Ericaceae, to which the genus Rhododendron belongs. However the jury is out about whether lime nectar actually poisons bumble bees, or whether bumbles continue feeding on lime nectar even when levels are low and so they run out of energy and collapse. It contains an andromedotoxin. I never really noticed bee activity on Rhododendron, but will now. The past 2 years it’s been a different pattern (and we’ve had more rain). It is made from the nectar bees gather from some species of rhododendron. And ultimately, we may also have a … I contacted the grower on the monday morning and he in turn was quite shocked. The common rhododendron, Rhododendron ponticum, certainly does produce toxic nectar. The best poisonous plants for honey bees are the plants in the family Ericaceae, particularly rhododendrons, which produce a lot of nectar and pollen. When bees create poisonous honey containing grayanotoxins, the nectar and pollen they collect, as well as the honey is not poisonous to them; only to humans. The Poisonous Plant Guide is constructed to enable location of a plant by either knowing the common or botanical name of the plant. It’s interesting that some toxins can actually be beneficial for bees. There are three categories of plants that are associated with toxic honey: 1) plants whose nectar or pollen kills bees before they can transform it into honey (e.g. The toxicity found in varieties of rhododendron is not uniform across all the plants' species, although it is a characteristic of Rhododendron ponticum, one of the most popular varieties of the shrub. Bees need flowers and plants need bees for pollination. It is most frequently produced and consumed in regions of Nepal and Turkey as a recreational drug and traditional medicine. Chemicals in rhododendron leaves, flowers and nectar make the plant toxic. The problem is only observable in the time gap from about 1 hour after dawn to mid day where the bees have pushed the dead bees out of the hive but not removed them from the immediate area in front of the entrance. Spectacular and beautiful, not many people know the common rhododendron hides a poisonous secret – its nectar is toxic to bees. I’m now convinced the bees eat something that is poisonous to them. Keep in mind that they bloom early, if the bees do visit them they'll likely use up any honey themselves before the main flow happens for us - and also you'll see bumblebees pollinating rhodies, but I've yet to see a honeybee in a flower. It … Bees need flowers and plants need bees for pollination. The first time it happened we suspected pesticide poisoning. Not all plants are safe for all pollinators. Hallo Emma, Last Saturday was the national Bio-dynamic beekeeper day in The Netherlands, a real red letter day so to speak. ); 2) plants whose nectar is harmless to bees but when turned into honey becomes toxic/inebriating to humans (e.g. Jane Stout and I wrote a grant together, but it didn’t get funded haha…otherwise I would have been in your neck of the woods. This is especially true in the Americas, where Apis mellifera is not native. As for the dead bees… they look normalish. Rhododendron honey is said to be toxic only if very recently produced by the bees, so commercially produced honey is unlikely to produce any effects. Actually, many plants have different levels of toxins in the nectar and sometimes bees will seek it out to “self-medicate” if they have a parasite or pathogen. The resulting honey from rhododendrons has also been known to contaminate honey, making it unsafe for humans to eat. If we do have R.ponticum near us, the research carried out by Professor Stout and Dr  Tiedeken suggests that our honey bees will probably avoid it; additionally the plants are likely to be less toxic than in their native range. It depends on the species of rhododendron – and also on the sub-species of honey bee visiting the rhododendron. Some species of rhododendron are poisonous to grazing animals because of a toxin called grayanotoxin in their pollen and nectar. Do the dead bees in front of your hives look different from normal bees in any way? Then at the end of the day, we can do have a fine, tasty, safe then non-toxic honey. If your dog eats part of a rhododendron plant, symptoms will usually start to be noticeable between one and three hours later. Yet research led by Prof. Jane Stout, Professor in Botany and Dr Erin Jo Tiedeken, Research Fellow at Trinity College Dublin, has found that its flowers are visited almost exclusively by bumblebees, with occasional visits from solitary bees, flies, ants and wasps. Other bees are simply dispatched – dead or wounded – leaving more food for the true friends of the flower. In the UK lime trees have been linked to bumble bee poisoning, as large numbers of bumble bees can sometimes be found dead under lime trees. Thanks for your thoughts anyone else too. Thanks, Emily. GUIDE TO POISONOUS PLANTS ... and weakness are reported in people who have consumed "mad honey" made by bees feeding on rhododendrons or who have consumed tea made from the leaves of rhododendrons. There are actually flowers harmful to bees. The rhododendron family of plants includes more than 700 species, but only a handful contain grayanotoxins: Rhododendron ponticum and Rhododendron luteum.Both are common in the rugged areas around the Black Sea. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. But, both species provide very enticing nectar for bees. That makes sense – it’s in the best interests of the plants to attract pollinators. Rhododendron honey is said to be toxic only if very recently produced by the bees, so commercially produced honey is unlikely to produce any effects. Instead, the rhododendron nurtures bumblebees that depend on its flowers, creating a stronger symbiosis. Although its nectar is toxic to man, honey from it quickly loses any toxicity. These effects vary based on the species of bee consuming the nectar, but they are lethal to some. €10,00 per tree. You leave it in the path of enemy troops, they eat it, and within a few hours are nauseous and disorientated. Rhododendron from the heath family (Ericaceae) is poisonous to bees and humans. The toxic chemical in rhododendrons is grayantoxin. For example, the nectar of rhododendrons is toxic to bees, and if bees ingest it and then make honey, it … This site uses Akismet to reduce spam. But as the water is driven from the nectar to produce honey, the grayanotoxin is concentrated to poisonous levels. It contains an andromedotoxin. Those bees produce a mildly toxic honey that was once allegedly used during wars to poison invading enemy troops. Insect problems include aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. It may be that the bush is not a rhododendron, or that something else is killing the bees. These types of toxins are usually produced by plants to reduce foliar grazing. My home is surrounded by 8 acres of rhododendrons. Check these links for more details (the first one is also a link in the article): Honeybeesuite - A rare case of honey intoxication in Seattle and Poison Control: Rhododendrons and Azaelas While regarded as poison, it's toxicity is somewhat overhyped. The goal might be wax, pollen, bee poison production or colony raising (nukes, package bees etc.). These apparently affect native and honeybees but not bumblebees. Lindy mentions above that Aesculus Californica (Calfornian Chestnut) trees are known to be poisonous to bees. It may be a mechanism to select specialists that are more effective at pollinating the plant.”. I saw the documentary about Nepalese honey hunters. He said: “In the book “Plants and Beekeeping” by F.N.Howes. Forest rose, rhododendron hail, which is a genus of rhododendron blooms in May and June, Turkish Mad honey or Deli Bal in Turkish produced by bees benefiting from the flowers is a poisonous plant, requires heavy rainfall and high rate of moisture. Change ), You are commenting using your Facebook account. Effects. I have no idea what it is. I know things will soon get very busy so am trying to write all the posts I can now before life goes crazy! These Rhododendrons have a toxin called grayanotoxin in their pollen and nectar. This is honey that is made from bees that have collected nectar from grayanotoxin containing plants, primarily Rhododendron. Indeed it would be impossible to keep the bees away from it, so I have likely consumed some, since it’s around everywhere at some times of year. ( Log Out /  Azaleas are very close relatives of rhododendrons and can cause the same type of toxicity. Rhododenrons may only be a problem for beekeepers surrounded by large areas of R.ponticum, which could smother out other plants and reduce the amount of forage available for honey bees. Sorry, your blog cannot share posts by email. In short it would probably be just fine, but for future reference the Indian Horse-chestnut ( Aesculus indica ) would be far better for the local bees as it flowers in the June gap and the nectar is not reported to be toxic to bees. Honey made from the nectar and so containing pollen of these plants also contains grayanotoxins and is commonly referred to as mad honey. very interesting; by the way I like the idea of “randy rhododendron fans”!! There’s quite a lot of information available when you’re buying rhododendrons, so check this when you’re buying. Most cases of … A fascinating post Emily, interesting to learn that bees may self-medicate and that rhododendron is poisonous to honey bees. “There are more than 700 different species [of rhododendron] in the world, but according to our knowledge just two or three include grayanotoxin in their nectars". As well as this aspect of the problem, most legislative councils are pro active in having useful bee forage plants in public areas these days so I don’t know what to do and would appreciate some input from you. Just two to three teaspoons of the spring honey made by Himalayan Giant honey bees (a subspecies of Apis dorsata) can result in temporary paralysis for a day or so, according to Mark Synnott’s article ‘The Last Honey Hunter‘ in National Geographic. This is news to me and I am glad to learn it. However, Irish research suggests the nectar may only have a negative effect on honey bees in countries where the rhododendron is an invasive species outside its native range – and even then, they’ll probably avoid visiting it anyway. I can’t help but wonder how common this kind of thing is but perhaps not noticed by beekeepers. Although the toxin can kill the bees, it is well diluted with water in the nectar. Botanists from Trinity College Dublin's School of Natural Sciences have discovered that the nectar from a common, non-native plant, is toxic to some Irish bees. I bought 3 Aesculus Californica young trees. Bees seem to build up well when foraging on R. ponticum nectar and pollen, but the author, who is a beekeeper on Colonsay, reports that every spring some of his bees show symptoms of poisoning. I’ve never heard any reports of rhododendrons killing bumblebees though, only honey bees. Glad your Akita was ok. Hopefully your reaction will have put him off eating any more! has probably evolved to resist the toxins in a similar way to the bumblebees. Toxic Honey Plants Rhododendrons. The grayanotoxin is the plant’s defence against herbivore attack. These apparently affect native and honeybees but not bumblebees. If you go out at dawn, the affected hive looks normal – no dead bees. locoweed [Astralagus lentiginosus], Veratrum californicum, Vernonia spp. Ingested, they … His nursery is too far away for me to take them back and he didn’t want to drive half way either… However, Irish research suggests the nectar may only have a negative effect on honey bees in countries where the rhododendron is an invasive species outside its native range – and even then, they’ll probably avoid visiting it anyway. Rhododendron Poisonous To Bees A. J. M., Berlin Heights, Ohio, writes: - "Two or three years ago I had some Rhododendrons which came out before the red clover, and would you think it, it was something new for Ohio humble bees . In conclusion, it sounds like rhododendrons are unlikely to cause British beekeepers many problems. Bees & Rhododendrons "Oh, they ate and drank & bragged no end about what they were gonna do. Rhododendron ponticum is known as a source of toxic nectar which causes bees to produce ‘mad honey’, used by European armies through the ages as a weapon of war. Mountain Laurel (Kalmia latifolia) also contains an andromedotoxin which can poison humans. I’ve asked lots of beekeepers and have been told vaguely that there are plants that kill bees but no one has any specifics (nor can I find them anywhere). In terms of appearance and flowering, that doesn’t matter too much but it has been found that the concentration of the main toxin is species/hybrid dependent so plants that appear to the layman to be identical may produce different degrees of poisoning.” – John Robertson, thepoisongarden.co.uk. Pingback: Rhodo Poison? I always thought they were a positive given how early they bloom. “Rhododendron is thought to appear in around 1,000 species and those species produce innumerable hybrids. The honey would be left in the path of invading legions; the soldiers would eat the sweet treat and end up vomiting and dizzy from grayanotoxin, a toxin contained in rhododendron honey. Rhododendron Species: yakushimanum Family: Ericaceae Wildlife Value: Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. “Mad honey” seems to be most prevalent in Turkey, in the Black Sea region, where locals can distinguish it from “good” honey because of its bitter taste (3). By Rasbak – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=800114. A very new area of research, I think! Botanists from Trinity College Dublin's School of Natural Sciences have discovered that the nectar from a common, non-native plant, is toxic to some Irish bees. It seems that bees that forage among rhododendrons produce "mad honey", which European armies have have been using as a weapon of war for centuries. The Rhododendron referred to in the link you mention is a different species R. ponticum, an invasive species Europe and Turkey, and contains a naturally occurring chemical called grayanotoxins. California buckeye (Aesculus californica) – has caused losses of honey bee colonies throughout its range. These Rhododendrons have a toxin called grayanotoxin in their pollen and nectar. Rhodies are not the only toxic honey source -- tansy ragwort honey is also regarded as toxic. In contrast the nectar has no apparent effect on worker buff-tailed bumblebees. Not all rhododendron honey is toxic, as not all rhododendrons contain toxic compounds. Now & then one encounters the folklorishly exaggerated "warning" that rhododendron flowers are so poisonous that bees manufacture toxic honey from them. Common rhododendron is regarded as an unwelcome alien invader and being eradicated from Nature Reserves here in North Wales, so not a good hunting ground for ‘mad honey’ here! They also tested the grayanotoxins on an Irish species of mining bee, Andrena scotica; this species did not suffer increased mortality but had its behaviour severely affected, for example becoming paralysed or spending increased time grooming. Pontic rhododendron (Rhododendron ponticum): Native to southwest Asia and southern Europe, this shrub is widely planted … A landscape scale chemical analysis comparing R.ponticum plants in Ireland with R.ponticum plants in the species’ native range of Spain and Portugal found that toxin levels were lower overall within the Irish plants. All of which I knew. I’ve long been intrigued by the idea that a plant could poison its pollinators. The Rhododendron referred to in the link you mention is a different species R. ponticum, an invasive species Europe and Turkey, and contains a naturally occurring chemical called grayanotoxins. I also happen to know that it is planted at the Sir Harold Hillier gardens as an ornamental, not far from the hives there, and I have not heard of any issues. This makes sense – rhododendrons bloom in the spring when honey bees may be distracted by other flowers. Yet, all species produce a very-attractive-to-bees nectar. +rhododendron +toxic +honey and then go on and replace the plant name with any other plant you might be worried about. In addition, honey produced in the spring during the rhododendron flowering season is mostly consumed by the bees and is rarely harvested. Being sterile, it does not produce seed. Any other suggestions? I hope this helps.”, So it sounds hopeful that the trees would not be a problem for you. At the moment I have time because I’m on maternity leave, with my baby due on 10th April. In addition, honey produced in the spring during the rhododendron flowering season is mostly consumed by the bees and is rarely harvested. Yet, all species produce a very-attractive-to-bees nectar. Strictly speaking In fact, the honey bee is perhaps the first “invasive insect species” brought by humans to the New World.

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