Hello,
so I promised to debunk some "common knowledge" or opinions based more on "anecdotic stories" than scientic eveidence. I will start with my own favorite - the danger of using autumn honey for the winter-in (usually it means heather honey and/or honey dew). But I will not write a big essay on this subject since the job is already done by Randy Oliver and here is the link to the full article that was published in ABJ in 2019-2020 with all references to read.
The Nosema Problem: Part 7b - The Causes of Dysentery in Honey Bees: Part 2 - Scientific Beekeeping
For those who dont have the energy to read dozens of white papers I give a short resume.
Now I assume most have heard that the bigger ash content would be an issue and that will cause dysentery? Well, if that is actually true then automatically honey as winter food is banned because how would we avoid getting a portion of autumn honey in the winter stores? It is virtually impossible and as a result many bee keepers rob the hives clean of honey in august and replace it with sugar. One thing that really bugs me - if this would actually be true then how would the bees have survived, before mankind came and aided them with sugar, in countries like Scotland, Brittain, Sweden coast, Norway etc where heather, in some cases, are the only nectar in abundance?
Anyways, in his survey Randy found that already back in 1935 a researcher named Alfonsos spent two winters to check what really caused dysentery and no type of food had any impact (neither honey, honeydew, heather honey, sugar or any mix of sugar) and that the only issue that did cause an impact whether dysentery would happen or not was the ability to get rid of the water (1 kg of food gives 0,67 kg of water during the metabolism) and when the hind gut is full of water then dysentery will happen. In addition, if the water content is too high that will make the situation worse (more water to get rid of) and also when the food chrystalizes and hence split into one portion with high water concentration and one portion of solid glucos which the bees have issues to dissolve, also add to the water stress. The bees can remove water by breathing, but when that is not suffiecient they will have to produce brood and calculations show that half a comb with brood use up one week of accumulated water. Another elegant test, by Möbus, where they caged the queen in a hive, confirmed that when they could not produce brood then dysentery would happen and it happened after some weeks.
Now, its fairly easy to calculate the ash content and if one do so its absolutely clear that the minerals will never cause issues. Furthermore, bees have rectal pads - which not all insects have - but thsoe who have use them to re-use the minerals. So with those two facts its pretty clear that minerals do play a vital role in the biology of the bees and that they rather experience a lack of them then have too much.
Then, if one does calculate the water that the bees have to get rid of (Randy does that exercixe) it will also confirm that it takes about 30-40 days before the hind gut is full.
Finally, there is very few studies where bees have been fed pure heather or honey dew but I have one report, from black forest, where the bees naturally forage honey dew and they saw no increased winter mortality compared to areas where no honey dew is found.
https://www.researchgate.net/public...on_the_stores_with_addition_of_honeydew_honeyI challenge anyone to come up with a study that shows either heather or honey dew to be an issue (not counting concrete honey which is one exception due to not containing any mono- or di-sackarids).
And lastly, we conducted a test in 2020 where our hives got 40-50% heather honey and all the colonies came out super strong without a trace of dysentery. This winter we do another test where we give 100% heather and compare it to 100% of summer honey. So far both hives have increased their weight with about 5 kg (started at 34-35 kg and now they are at 38-39 kg). We use 3 boxes of size LN that probably equals 2x Langstroth.
Cheers
Mikael