Medicinal herbs for bees – an experiment

The Editor
ABK.
I wonder how many beekeepers around Australasia are tired of losing hives to AFB and would like to try a new approach. Nothing ventured, nothing gained. Several books tell of European beekeepers taking their bees to herb fields to restore the bees’ health. Elsewhere, several plants are described as being “good for bees’ health”, etc.
A story did the rounds of south-east Queensland ten years ago of a beekeeper whose hives, surrounded by a large herb garden, escaped the AFB that almost wiped out surrounding apiaries. All of the stories are short on detail, and I would love to hear from anyone who can document and verify similar claims.
Also, I invite all beekeepers, large and small, with at least one fixed apiary site, to join me in testing whether there is any truth in stories of certain plants having the ability to prevent or cure bee diseases.
As a scientist, I accept that many “scientific discoveries” have arisen from good old practical experience and observation. It’s time we took a serious look at the science behind what the traditional beekeepers of Europe have been doing for generations. After all, the European honeybee is an exotic species in Australia, operating on flowers that are foreign to it. Few Australian pollens contain all of the ten amino acids and two fatty acids that bees must obtain from pollen to develop fully into strong adults. Then there is the matter of remaining healthy while being bombarded by all manner of biological threats. Rob Manning of WA Dept of Agriculture has identified two fatty acids found in some pollens that are able to kill AFB. The nutritional fatty acids are palmitic and oleic. The two found to be effective against AFB in laboratory tests are linoleic and linolenic. 
Rob Manning asserts that an antibiotic pollen in one cell of a brood comb will sterilise seven cells, as the fatty acid (oil) in the pollen only needs to soak through one wall of a neighbouring cell to kill the bacteria. So it looks as if science and legend might meet.
My experiment began by trying to find plants with linoleic and/or linolenic acids in their pollens, because these are believed to be effective against AFB. About a million internet hits on these chemicals did not seem to lead to plants. Next I looked at descriptions of the plants reputed to be good for bee health. Wikipedia had nothing on pollens, but some data on other parts of medicinal and culinary plants. Any aromatic oil found in part of a plant will generally be found throughout that plant, but the concentration will generally vary. Any chemical listed in leaves, stems or flowers, I assumed would be present in the pollen. 
On this basis I selected fifteen species of herbs/small bushes to be planted in irrigated beds in a bee yard where I live. Brief details are set out in the list below. Only one,Borago officinalis, has all four of the fatty acids identified by Manning. The others have reputations or contain chemicals claimed to have antibacterial properties. Apart from control of AFB, the fungicidal properties claimed for some of the herbs might be effective against chalkbrood. Insect-repellent properties of others might apply to ants, small hive beetle or wax moth. If we don’t give it a go, we’ll never know.
My experiment is in the early establishment phase. During the 2011/12 season the plants should be flowering and having their effect, if any, on the hives in that yard. For comparison, I have two small apiaries about 500m west and about 300m north-east of the herb garden/apiary, and two others a little over 3km west and 3km north respectively. Apart from the medicinal(?) herbs in front of the central apiary and a mango plantation near the western hives, all sites have a similar mix of native species, crops and weeds (“wildflowers”). If the herbs are 100% effective at preventing disease, there will be no disease in the hives in the herb garden, some disease in the nearby hives, and more disease in the hives 3km away. If the herbs are 100% effective at curing disease, hives found in the early stages of AFB and brought to the herb garden should be cleansed of AFB and should survive. (I’d still be sending stickies to Steritech ‘though!)
Such a clear result would be rare in scientific research, and a single result would carry little weight. To really test whether these or other plants can cure or prevent bee diseases, we need beekeepers all over Australasia to plant herb gardens close to fixed-site apiaries, and to report their observations. Another approach would be for beekeepers to site bees in established commercial herb gardens if the herbs are allowed to flower. If there is a general trend to support a belief in medicinal plants for bees, it would warrant more formal scientific research. 
I would really appreciate your bringing this to the attention of your readers, and disseminating any feedback.
Yours sincerely
John Tadman.
Ph 07 5496 7296 Fax 07 5496 7515

Some species of plants with possible medicinal value to honeybees (not an exhaustive list)

Annuals

Borago officinalis,  Borage, is a self-seeding annual herb that will bloom continuously for most of the year in mild climates.  It is reputed to be the highest known plant-based source of gamma-linolenic acid, and also contains palmitic, oleic and linoleic acids, plus four others.

Matricaria recutita, German chamomile, does not appear to have any of the two (or four) fatty acids in which we are interested, but has been included because of its “acaricidal properties against certain mites” (Varroa was not mentioned) and the claim that it is thought to be useful to suppress fungal growth.  German chamomile is a self-seeding annual.

Coriandrum sativum, Coriander, an annual “loved by bees”.  No analyses.

Tropaeolum majus, Nasturtium, is used as a human-medicinal plant, is said to be antiseptic, but no analysis readily available.  It is a perennial often treated as an annual.

Perennials

Hyssopus officinalis, Herb Hyssop, “is commonly used by beekeepers to produce a rich and aromatic honey”.  It contains thujone and phenol, which give it antiseptic properties.

Thymus vulgaris, Thyme, contains the powerful disinfectant called thymol that is effective against bacteria and fungi.

Origanum vulgare, Oregano, contains carvacrol, thymol, limonene, pinene, ocimene and caryophyllene, which make the leaves and flowering stems strongly antiseptic.

Rosmarinus officinalis, Rosemary, “repels moths and flies, liked by bees”.  Eight bioactive compounds are listed by Wikipedia, including camphor, which is consistent with the claim of repelling moths.

Salvia officinalis, Sage, contains oleic acid plus numerous other compounds which give it antibiotic and antifungal properties, to mention only two of the claims.

Echinacea purpurea, Echinacea, Eastern purple coneflower, is commonly believed to stimulate the immune system in humans, so this might extend to other animals including insects.  No data.

Nepeta cataria, Catnip, Catswort, or Catmint, is “a good bee plant” that contains nepetalactone which is a mosquito repellent.  No further detail.

Allium schoenoprasm, Chives, and Allium tuberosum, Garlic chives, have “flowers attractive to bees”.  Chives are said to be repulsive to insects in general, due to sulphur compounds, but attractive to bees, “and it is sometimes kept to increase desired insect life”.

Melissa officinalis, Lemon balm, or Bee herb, is attractive to bees and contains eugenol which kills bacteria.  Lemon balm also has anti-viral properties.

Monarda fistulosa, Bee balm, Wild bergamot, is attractive to bees and contains thymol.

It is interesting to note that five of the fifteen species above, from fourteen genera, have the same specific name, officinalis, which refers to the plants’ medicinal use.  The officinawas the room in a monastery where herbs and medicines were stored.

Author:  John Tadman