Photo credit: msnbc.com
A few weeks ago Dennis received a call regarding a Maryland beekeeper concerning what was believed to be a pesticide kill. Throughout the conversation it was learned that there was an abundance of the common pasture weed, buttercups (Ranunculus species), growing in close proximity to the hives. The beekeeper noted that the bees appeared to be struck with a form of paralysis, twitching and exhibiting convulsive movements. While we are not ruling out a pesticide kill (the samples are still being tested), there have been cases where bees have been poisoned from ingesting buttercup pollen. Since it was mentioned that there were buttercups blooming nearby in this case, we decided to take a closer look.
Buttercup pollen grain
Buttercups flourish abundantly in the warmer months. I am sure you are familiar with their bright, yellow flowers littering yards and pastures. The weed contains a chemical called anemonol which breaks down into the toxin protoanemonin, which is highly lethal to bees. When the plant dies, the protoanemonin no longer retains its toxicity as it is only present in the growing buttercup. However, pollen collected from a buttercup can retain deadly protoanemonin for a period of up to three years. Right now, buttercups are in full bloom creating a haven of toxicity for unsuspecting honey bees.
When bees eat this stored pollen they experience certain symptoms from the poison within minutes. Paralysis, body convulsions, and leg twitching can affect not only workers, but drones and queens alike. A number of titles have been given to identify these strange symptoms from Ranunculus poisoning such as May disease and Bettlach disease.
Buttercup pollen grain
We were rushed a sample of bees in alcohol, buttercups picked from the area and a frame chock full of pollen taken from the hives. I identified the buttercup pollen and crushed up the bees to see if there was any buttercup pollen in their mid gut; however, there were very few traces of pollen found and it did not appear to be from the buttercups. I had higher hopes to find some in the frame, however when I took a look at the pollen on the frame I found no buttercup pollen. It will be difficult to find out if buttercup pollen is really the cause of these unusual symptoms through pesticide analysis because protoanemonin is naturally occurring ‘pesticide,’ so there is no specific pesticide test for it. Because the samples are being analyzed for pesticides; however, we will be able to see those levels of man-made pesticides, possibly leading us to another conclusion, but until then, the mystery continues…
I wondered if the pollen could id the pollen in the feces or pollen basket loads found on the bottom board?
This is the most ridiculous explanation for CCD I have ever come across. Bees and flowers haver evolved together for millions of years in perfect symbiosis. Bees are highly intelligent creatures that would not forage on flowers that are toxic to them. They only die after taking pollen from flowers they naturally visit when these flowers are poisoned by men.
Actually, honey bees have not evolved perfectly with all flowers. Honey bees evolved in Europe and Northern Africa and not in symbiosis with many of the new world plants. I work with a number of beekeepers in southeast TX that have huge issues with bee deaths due to yellow jessamine (or jasmine) vine, Gelsemium sempervirens. One even moved their queen breeding operation due to the large kill of the queen cells and bee brood. I wrote a blog about Cyrilla racemiflora that turns brood purple and kills it. I wouldn’t say that plants are the cause of CCD (and I don’t think Jennie was claiming that either), but they can definitely cause bee losses.
This is a great article, as it is one of the few I’ve found on the topic. Is there a way to know for sure if the bees are foraging? I’ve got roughly 2 acres of mowed pasture area, and the buttercups are relentless, appearing shortly after the dandelions. My bees *should* have others sources of nectar/pollen, and I *hope* they are going for those sources, but what am I to do if I’m invaded by buttercup?
I don’t see ANY bees on the stuff, but I haven’t checked each of the hundreds of thousands of them on my farm. However, I do see some of the bees in the hive are covered in yellow pollen. That could be the dandelion, but I’m kinda worried that it is not.