Hi all,

I´ve been following with interest the thread regarding how to use fumagillin efficiently.  

Two years ago, the University of Mar del Plata and our company got a grant to investigate both the prevalent strains of Nosema present at our hives and alternative active ingredients to fumagillin. At the same time we were interested to find out the efficacy of two different active ingredients (thymol and thimerosal) against the two haplotypes of Nosema. 

Although a research paper has already been written and accepted for publication at peer-reviewed journal, I would like to pass on some of the most interesting findings.

At least in the temperate region of Argentina, Nosema apis is almost extinct.  After conducting PCR with the appropriate primers,  we found out that Nosema Apis has been entirely superseded by Nosema ceranae. This reminds me what Ingemar Fries told me when I attended the last symposium on bee diseases organized by the O.I.E. and Apimondia in Freiburg (Germany) during August 2008: «We must create a sanctuary to avoid the extinction of Nosema apis...»

We tested fumagillin, thymol and a little known but old product which is called Thymerosal. The later is a mercury salt, its use was popular in Germany back in the 1950´s and 1960´s, it was part of the commercial product NOSEMACK. According to research papers of that time (kindly provided to me by Dr. Tom Sanford), thymerosal was quite effective not only against the sporular stage of Nosema Apis but also against the vegetative stage.

Considering the long and widespread use of fumagillin since 1954 as well as its recent intensification, since the recognition of Nosema ceranae, it is a miracle we still do not have resistant strains of this parasitic fungus. Whatever new alternative would be quite welcome. 

However, thymerosal (also used as an sterilizing agent in vaccines) is extremely toxic to bees even at very low doses. The preliminary observations would indicate that nosema affected bees were the first to die, but the fact is that even healthy bees also succumb. It is also very risky in terms of residues. However, being a queen breeder and restricting its use to just mating nucs and queen cell raising hives, its use should not be dangerous. Anyway, the impact on bees was quite hard so we do not consider it a valid alternative.

Thymol into patties would be an interesting alternative for an IPM strategy focusing at decreasing the level of nosema spores over a long period of time, let´s say between 3 to 5 years. But you can´t trust thymol for an immediate knock out on Nosema infection.

Concerning fumagillin, we noticed that the total amount of active ingredient to suppress Nosema ceranae is 140 miligrams per hive, applied during a period of four weeks, each time providing 35 miligrams in not more than 500 cubic centimeters (half a liter) of sugar syurp. When providing the same 35 miligrams dose in more than 500 CC, the efficacy was lower. I know this is in contradiction with the label provided by the manufacturer who sells the product, but the results were much better when supplying a very concentrated solution. Each dose was administered into an internal feeder. We did not use the drenching method.

Last year, I was very enthusiastic about the new product Nozevit from Croatia. Although not labeled for Nosema control, the advertisement as well as its brand name suggests it is effective against this disease.  I had initially bought a 50 CC at the Bee Convention held in Sacramento during 2008, then at Apimondia 2009 in Montpellier I got a very expensive full liter (1,000 CC) for 140 euros. 

During the Spring of 2009 (Sept. Oct. in the southern hemisphere) I ran a trial with 15 hives: 5 control, 5 fumagilin and 5 Nozevit. After a month, 4 of the 5 hives under the fumagillin treatment had no detectable levels of nosema, however one of the hives still had substantial amounts of spores but this was due to lack of consumption of the medicated syrup. The five hives under the Croatian product and the control hives had very similar levels of Nosema spores. Although, the intestinal integrity of the treated hives might have been improved, in terms of Nosema control under our temperate conditions in Argentina, the results were not satisfactory.

It is unfortunate that none of the products so far used in the silk worm industry to control Nosema bombycis cannot be used to stop Nosema ceranae in honeybees. How long fumagillin will be effective for Nosema disease is something I do not know. Trials to use albenendazole were not successful.

Sincerely,


Martin Braunstein
MALKA Queens
www.malkaqueens.com

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