We are nearing the end of July and the weather has been warm lately here in Atlantic Canada! With all this warm weather, just like us and other animals, our honey bees need to stay hydrated to beat the heat and maintain proper colony function. Honey bees access water from a variety of sources but did you know they have specific preferences depending on the mineral content of the water? A recent study investigated honey bee mineral preferences in water. Keep reading to find out more about what preferences honey bees have for minerals in water and why they might have these preferences.
Speaking of water, we are nearing the typical drought and dearth season for the Atlantic Canada region. This year we are seeing more rain than last year, which is great, but we still need to keep an eye out for signs of drought and dearth so we can provide our bees with necessary resources as they are needed. If a dearth period is brought on by a drought, beekeepers can help their colonies along not just by providing sugar syrup feed but also by providing a nearby water source for their bees!
Ratios Rather than Concentrations of Nutritionally Important Elements May Shape Honey Bee Preferences for ‘Dirty Water’ *
Honey bees have nutritional requirements, just like all
other animals. Often when considering these nutritional requirements, nectar
and pollen are identified as the suppliers of these nutrients for honey bees.
However, nectar and pollen alone are not always able to provide all the
minerals that honey bees need to satisfy their nutritional needs. One way honey
bees increase their mineral intake is by drinking ‘dirty water’, or water that
contains these essential minerals. A recent study investigates the preferences
of honey bees towards a selection of ‘dirty water’ offerings containing various
ratios and mixes of minerals. This is a novel approach to exploring mineral
preferences of honey bees since it incorporates comparisons of various mixed
mineral ratios and concentrations, rather than only comparing individual
mineral concentrations as has been carried out in past studies. The minerals
used in this comparison include:
- Sodium chloride (NaCl)
- Potassium chloride (KCl)
- Calcium chloride (CaCl2)
- Magnesium chloride (MgCl2)
- Ammonium chloride (NH4Cl)
- Potassium dihydrogen phosphate (KH2PO4)
These minerals were mixed in water in various configurations
of ratios and concentrations to yield the four mineral solutions used in this
investigation:
In addition to these mineral solutions, deionized water was
offered as a neutral control and 20% sucrose solution was offered as a positive
control.
Samples of bees were collected and offered these liquid
options under constant observation for 1 hour time slots. The results of these
observation indicate:
- A significant preference towards the mixed solution (‘Mixed molar conc.’ in the above table) compared to other mineral solutions and the neutral control
- A preference towards the mixed solution compared to sucrose solution in the afternoon, but vice versa in the morning
The study at hand suggests that the preference towards the
mixed solution compared to the other mineral solutions could be explained by
the high Na:K (sodium : potassium) ratio in the mixed solution. Since animal
tissues contain much higher levels of Na than plant tissues which are higher in
K, honey bees have a natural preference towards solutions containing higher
ratios of Na:K when presented with options of varying ratios. This is further
supported by the importance of Na in the honey bee diet, which is highlighted
by the example of acute bee paralysis potentially being caused by a diet with
too low a ratio of Na:K.
The observed preference towards sucrose solution over the
mixed solution in the morning, but then a preference towards the mixed solution
over the sucrose solution in the afternoon could be explained in terms of
energy supplementation. The study suggests that bees prefer the sucrose option
in the morning since it is a carbohydrate and will provide the bee with an
energy source. Once this carbohydrate energy requirement has been satisfied,
then the bees will forage to meet their other nutritional requirements.
Understanding what honey bees need and what their natural
preferences are can help beekeepers better support their colonies, especially
when it is most needed. Natural supplies of these mineral-rich waters include
puddles and other accumulations of water in naturally mineral-rich substrates.
* Cairns, S.M., Wratten, S.D., Filipiak, M., Veronesi, E.R.,
Saville, D.J. & Shields, M.W. (2021) Ratios rather than concentrations of
nutritionally importance elements may shape honey bee preferences for ‘dirty
water’. Ecological Entomology, https://doi.org/10.1111/een.13067.
Full text available ONLINE.
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