Hi all.  At the annual meeting I was asked to write up the Terramycin (TM) / powdered sugar ratios for proper mixing and application for treatment of AFB.  I am happy of course to get this is The Buzz, but have hesitated to do so without at least a couple thoughts on TM usage in our beehives.

There was a good deal of conversation at the Annual Meeting about the sort of “weak, sickly” bees we raise and keep due to our reliance on the various chemicals (miticides, antibiotics, etc.) we use in our hives.  Usage of antibiotics discourages the development and maintenance of natural, strong “immune / defense” systems in our bees.   We are directly breeding weaker, more susceptible bees by sustaining colonies chemically rather than genetically.

Further, once you start a program or routine of antibiotic usage in your beeyards, it becomes difficult / dangerous to break the habit.  Terramycin (and Tylan) are antibiotics used by beekeepers for the control of Foulbrood.  Until resistance builds up (which is a matter of time) the chemicals work to keep colonies healthy, or at least relatively free of any symptoms of AFB infection.

We are very fortunate that Phil Ebert has been documenting each month in The Buzz his fight to wean his bees off of dependence on antibiotics.  The issues he has shared concerning AFB flare-ups and how they treat the colonies / hives as symptoms do appear are a valuable example that the AFB was always there, kept mostly in check by the chemical treatments but always present. 

The general (and difficult to argue) notion is that the more hives one has, the more they have to lose in the event of AFB infection.  And it’s this level of risk which brings a large number of beekeepers to dependence on antibiotic treatments to protect their investment.  This is often referred to as the “treadmill” – once you start, it’s difficult to get off.  Dependence and resistance builds up increasing risks of stopping treatment and leading to the use of newer, different, potentially stronger chemicals.  The Beltsville USDA Lab has confirmed many times that Terramycin-resistant strains of AFB are being found here in Iowa.

If you start with prophylactic use of the antibiotics and AFB spores are brought into the colony, say by the bees robbing out an infected colony or by the sharing of honey supers which were previously used on an infected colony or by transfer by the beekeeper’s equipment as he works colony to colony, those spores remain in the colony – basically inactive until the antibiotic treatment is discontinued. 

One recent related example is of a complete hive with a colony that was bought used by a central Iowa beekeeper this spring.  The hive wasn’t inspected at the time of sale but I inspected the beeyard in early summer.  It looked clean and strong.  This fall the colony crashed, apparently due to having swarmed without successfully replacing the queen.  I took another look at the empty hive and found signs of a low level of AFB infection – spotty brood pattern, perforated cappings, ropiness of dead larvae.  No scale and no strong Foul smell. Knowing who the hive was purchased from, I’m confident that it has always been treated with antibiotics, but this season it wasn’t treated by its new owner.  The inactive but viable AFB spores became active and by fall had built up to a decent level of infection.  This sort of example should be kept in mind by anyone purchasing used equipment – effective treatment of low levels of AFB infections can mask all observable symptoms.

It’s the same basic situation, only more extreme and more concerning, when the antibiotics are used as treatment in infected colonies already showing symptoms of AFB problems.  Too often, the treatment is applied and the AFB symptoms disappear.  The colony is sort of “superficially healthy”.  The spores don’t leave, they remain viable for decades, and they already exist in the colony in large concentration.  This breeds resistance to the treatment creating even more dangerous strains of AFB.  It also presents a direct problem for neighboring colonies of bees which can potentially bring the spores into their hive in events of robbing if the infected colony crashes say due to Varroa or winter loss, etc. 

Most of us who use TM are using the little 6.4 ounce bags of “Soluble Powder” (TM25).  You can purchase these from just about any of the bee suppliers or at most local farm supply stores.  I saw it yesterday at TSC, for example.  The common method of application is to dust a mixture of TM and powdered sugar over the topbars.  One 6.4 oz. package of TM soluble powder is mixed with 2.7 lbs. of powdered sugar. 

Once the mixture is prepared, simply apply the dust across the frames’ top bars.  Three 1ounce dustings at 4-5 day intervals are recommended in, both, the spring and fall.  Be sure to make you final springtime application at least 4 weeks before adding supers for the honey flow to prevent contamination of marketable honey.  Prepared as above, one 6.4 ounce bag of TM25 will treat 16 hives the recommended three treatments each (48 individual 1 ounce treatments).

Keith Delaplane has a good factsheet out on TM usage.  It’s several years old but the information is pretty up to date and it includes a number of tables to assist in mixing the TM25 soluble powder, TM50, and TM100 concentrations for application.

http://www.ent.uga.edu/bees/disorders/Terramycin.htm

Thanks. Andy

One update (already):

The day after I wrote this all out, I received an email from Jerry Hayes and then another one from Bart Smith (Beltsville USDA Bee Lab).  It seems that Pfizer is in the process of discontinuing Terramycin in the TMSP, TM50, and TM100 forms.  Terramycin will apparently still be available and labeled for use in hives, but only in a more concentrated form called TM343.