Invert Sugar Syrup: Not good for bees!
A reader email last week prompted me to go back over some of my notes from BeeMasters to talk about toxic sugar syrup. Unfortunately, my notes on our reader’s particular question (on stored syrup) were insufficient, so I’ll have to do a bit more work before we get to that.
In the meantime, I did want to write about another kind of potentially bad syrup; liquid invert sugar produced by acid hydrolysis. This is a syrup that is produced by adding a weak acid (i.e. lemon juice) to sugar syrup to break it down into simpler sugars (fructose and glucose). Some beekeepers do this in the hopes that it will make the syrup easier for the bees to take up and digest. Honey, after all, is made up of fructose and glucose, not sucrose.
I don’t want to inadvertantly misquote or misinterpret the science-y part, so here’s a direct quote from our course notes (emphasis is same as in the notes) :
Liquid invert sugar syrups or HFCS produced by acid hydrolysis are NOT recommended for feeding bees because they often contain a by-product known as hydroxymethylfurfural (HMF). HMF causes gut ulceration and mortality in bees. Often, acid hydrolyzed sugar syrups appear yellow or golden in colour.
In another part of our notes, it says that “…long term survival is greater with sucrose than inverted sugar products.” (no direct reference given to the source of this particular assertion; there is a bibliography for the whole section of notes in my course material – send me an email if you want the list of all the sources)
So, although there are recommendations and instructions all over the internet about feeding invert sugar to your bees, it’s not something we will be doing or recommending!