To feed bees or not to feed bees? If you read Jeremy Barnes letter to the editor (in most recent ABJ, September 2020) you might wish to hit the pause button. Jeremy summarizes studies involving feeding sugar syrup to bees confined in cages in the lab. Worker bees fed sugar syrup do not live as long (compared to bees fed honey), the different pH may disrupt the normal gut microflora, the pure sugar diet might overwhelm body functions evolved for nectar and/or the bees fed sugar syrup may have different genes activated (or not activated) when fed sugar syrup compared to bees fed honey. Whew – those could be significant changes!
However we need ask the question how much do studies of bees in cages in labs necessarily tell us about the bees we maintain in our colonies? Is it necessarily harmful for beekeepers to supplement the bee diet with a processed food? Bees only eat processed food.
Bees depend on sugar for energy. The nectar bees collect is a complex mixture of the sugar sucrose, smaller amounts of other plant sugars along with even smaller amounts of vitamins, minerals, plant polysterols, enzymes, colorants and chemicals unique to the plant. Sugar and nectar must be broken into the two simple sugars of glucose and fructose by the enzyme sucrase before use. This is the processed food honey. By definition “honey is flower nectar or the secretions of living parts of plants or honeydew (excretions of plant-sucking insects) that is deposited, dehydrated and stored in honeycomb.” [Language of proposed Food Chemicals Codex Identity Standard]. At the cellular level sugar source is immaterial.
When we husband animals or keep animals as pets we need to be prepared to properly care for them, even those that range freely. We feed sugar syrup to stimulate, we feed sugar to allow continued growth during dearth or changing environmental conditions and now most of us are feeding heavy sugar syrup to promote successful overwintering. We have a long history of feeding our bees sugar with no apparent ill effects. Though some may disagree, feeding sugar is reasonable bee stewardship.
Sugars to feed
Our normal choices of sugar to feed bees includes pure (99.95%) sucrose (table sugar), sucrose with a small amount of fructose (Drivert), a mixture of glucose and fructose (Invert sugar), corn syrup of 55% fructose with 42% glucose (HFCS-high fructose corn syrup), sugars that have additions (such as molasses) or syrups from other sources (agave) or incompletely processed sugars (brown sugar). Also there sugar substitutes plus of course honey.
We have to be very cautious feeding bees incompletely processed sugars, or those with significant additions; the sugar substitutes are potentially toxic and not sweet to bees. However we also have to be sure the sugars with fructose have not been improperly heated or stored because of the possibility of the buildup of HMF – hydroxymethylfurfural, a sugar toxic to bees (and humans). Bees and our diet can tolerate small amounts of HMF.
White granulated table sugar, is probably the purest, cleanest food in your home! It is completely digestible by honey bees with no residue, an important factor when we feed it during the winter. Sucrose is stable; it does not decompose. Kept dry it will last for countless years. When we mix it with water its breakdown by sucrase creates water as by product, meaning if we feed it during winter we might add to colony moisture stress. To avoid this we can feed the granulated (crystalized) sugar as a solid on top of inner cover or in a top feeder.
Better yet, we can solidify it into a sugar candy. A quick recipe is 10 pounds of white granulated sugar to 8 ounces of water. Let it dry overnight in a container to harden and then put over the colony. Warm moist metabolic water that escapes the winter cluster makes a slurry of the candy so bees can feed on it.
Invert and Drivert sugar
Invert sugar, used by commercial bakeries, is made via acid hydrolysis or enzymatically. Beekeepers make invert sugar, called fondant, by boiling a solution of sucrose and water. Recipes are available from numerous sources. It is best you not add an acid (lemon juice or cream of tartar (=tartaric acid) as the acid, plus the high temperature, whether prepared commercially or on your stove, promotes HMF formation. An uncooked fondant can be made by just mixing sugar with honey or high fructose corn syrup.
Bakers Drivert sugar fed dry is a good winter choice. It has been further milled to a finer crustal size. The small amount of fructose keeps it from caking but is not enough to lead to buildup of HMF. It is harder to obtain since only some 3% of the total sugar market is drivert. This is the sugar bakeries use for fillings and frostings.
Honey does contain fructose but as stored in the hive by the bees contains little HMF. Tropical honey has higher HMF content. However, repeated heating or storing at high temperatures increases the amount of HMF. Left at room temperature for a very long time HMF will increase. but still remain low. The very small amounts of color and flavor compounds in nectar are not in toxic quantities in the finished honey.
Dedicated to Ann Harman
See Column Sugar in February 2017 Bee Culture of recently deceased Ann Harman for further details on sugars for bees. She concluded her review “A well-fed bee is a happy, hard-working bee… Feed if necessary. Your bees will appreciate that attention”. We will miss her solid advice each month in Bee Culture. May she Rest in Peace.