Keeping combs of stores from lost colonies ?

[greengumbo]

Just a quick one. I finally checked to be sure a colony had dies out and right enough nothing left but a frozen queen clinging to a frame and a heap of dead bees on the floor. Almost certain they died out due to a small cluster and given the amount of dead bees it was even smaller than I thought. HM only stareted laying in mid-september after 2 drone layers over the entire summer so not a huge surprise !

Question: 3 of the frames are chock full of stores and there is no sign of disease or mould. Can I take these out and use them to supplement another hive ?

[Jon]

I do this all the time but to be safe I fumigate the combs with 80% acetic acid for a week.
This is supposed to kill everything except AFB spores and you should know if a colony had AFB from other well documented symptoms.
Putting combs in a freezer for a week will also kill a lot of nasties which may be present such as nosema.

I have lost a few nucs this winter exactly as you describe, wee small cluster with a queen still present.
They just did not build up properly in the autumn so there was a shortage of winter bees.

[Poly Hive]

I would suspect given the weather Aberdeenshire has had that these combs would have been exposed to enough freezing temps already.

PH

[Jon]

Randy Oliver reports that freezing is very effective and that just leaving equipment out in the cold for a month is a useful exercise.


Sterilization of Combs/Viability of Spores

OK, so let’s say that you’re the cautious type, and still want to kill any N. ceranae spores on the combs of your deadouts. Acetic acid vapors and radiation are options, and Dr. Cramer has found that bleach or lye also work.

However, Dr. Cramer reported some very interesting observations when I first supplied him with spores from my yard back in early 2008. He found that when he put the spores into the ‘fridge over the weekend, that a lot of them appeared to die (become nonviable) over the weekend! This was a great surprise, since N. apis spores are routinely frozen for storage, and spores in general survive better when chilled.

Dr. Cramer (unpublished data) analyzed groups of 10,000 spores. They started at about 87% viability. After only an hour in the refrigerator, viability dropped to 70%. After an hour in the freezer, viability dropped to 10-50%. At -80ºC (-112ºF) for an hour, generally only 5% of the spores survived. These are preliminary figures, and he is continuing this line of research.

At about the same time, Dr. Ingemar Fries and Eva Forsgren in Sweden also were having troubles at infecting bees with frozen spores. They’ve quite recently (2009) published some stunning similar results (by the way, Google translate does a great job going from Swedish to English). I’ve superimposed English labels onto his graph below.

Effect of chilling on the infectiveness of nosema spores. Unchilled spores of both species (bottom bars) infected 80% of the bees with a 1000-spore dose, and 100% with a 10,000 spore dose. The infectivity of N ceranae spores dropped substantially after a week of refrigeration, and dramatically after a week of freezing. Modified from Fries (Bitidningen 107, 2009) by permission.

Note: The above study has important implications to beekeepers. What is tells you is that in most of the U.S., winter freezing should be enough to kill most of the spores of N. ceranae! This supports the observation of a number of commercial beekeepers that letting deadout equipment “rest” for a month at cold temperatures resulted in better colonies when restocked in the spring.

When I and other researchers first heard of this observation, we scratched our heads, since in general, spores of disease organisms remain viable when stored at cold temperatures (there is normally more degradation at higher temperatures). None of us would have guessed that N. ceranae spores would be so intolerant of cold storage!

A very interesting additional observation by Fries was that N. apis spores actually appear to become even more infective after exposure to freezing! Note in the graph above how the 1000-spore inoculum of N. apis infected 100% percent of the bees after having been frozen—a higher percentage than with unchilled or refrigerated spores! Dr. Fries is planning further investigation into this surprising phenomenon.

The susceptibility of N. ceranae spores to freezing may help to explain why it appears to be more of a problem in warm areas. This point should not be lost on those Midwestern beekeepers who take colonies to California for almond pollination—any deadout equipment there won’t experience the “sterilizing” effect of cold winter temperatures.

So what if you live in a warm climate? You’re still in luck, since ceranae spores appear to be rather fragile. Dr. Cramer also found that they succumb quickly to elevated temperatures, to wit, 120°F for 90 minutes. Cramer hopes to develop a time/temperature curve of spore mortality, so that a beekeeper can determine how much time at what temperature it takes to kill most of the spores.

http://scientificbeekeeping.com/nosema-ceranae-kiss-of-death-or-much-ado-about-nothing/