Drought and the water content of nectar
I’m using the following question as a post, partly because it’s a good question and partly because the math stressed my brain so much that I’m going to split wood for the rest of the day. The question came from Carol in Wisconsin.
Here in West Central Wisconsin we are experiencing drought conditions, like many parts of the country. The nectar flow usually slows this time of year in normal conditions but this year is very dry. I have two hives which got a slow start and are still working on, or rather thinking about, drawing comb on the 4th medium (I use four medium supers instead of three deeps). I gave both hives 1:1 syrup with Optima this morning in hopes they would get on task. One hive has gone through 1/3 quart in 4 hours and the other is a bit slower. They have lots of foragers but there doesn’t seem to be much nectar and pollen coming into the hive.
My questions are:
Since cured honey is 17%-18% water content, I would assume that nectar is about 83% water. With no rain since June 15th, am I correct to assume what nectar available is already highly concentrated and the overall usual abundance greatly reduced?
There doesn’t seem to be any pollen coming in on the bees either. I gave each of the four hives a pollen patty and they are consuming the substitute with enthusiasm.
It’s also very hot, in the 90′s with an occasional 100+ temperature. My bees are all over the water (they prefer fresh supplies of well water at least once daily) which I know they use for cooling the hives but could they also be diluting what nectar they bring in to feed brood?
I also see one of my hives drawing and filling/capping one frame at a time in their honey super. Isn’t it usual for some workers to draw the all foundation and other workers fill the ready cells?
You are correct that honey is about 17% water, but it doesn’t follow that nectar is 83% water. (Actually, nectar is said to be about 80% water, but that is a convenient average that depends on the specific plants and the conditions under which they are growing. Water can be as low as 50% or as high as 92% of the nectar.)
But assuming nectar is 80% water and 20% sugars, and you want honey that is only 17% water, 100 grams of nectar will lose 75.9 grams of water and produce 24.1 grams of honey that is 17% water. It works like this:
Starting with 100 grams of nectar, x [the grams of honey you get] = 20 [the grams of sugars you started with] + (0.17x) [17% times the grams of honey you get). In other words:
Periods of low rainfall may produce nectar that is slightly higher in sugar, but not dramatically higher. Nectar that is too thick would gum up the plant’s vascular system. More likely, flowers just produce less nectar than they would otherwise.
When plants are stressed by lack of water, they may produce fewer flowers, less nectar, and less pollen. Flowers, nectar, and pollen are all part of the reproductive mechanism. Under heat stress, a plant puts its resources into surviving rather than reproducing.
Bees use water for evaporative cooling and for diluting honey that is crystallized, and it is consumed by nurse bees for the production of brood food. Water would not be used to dilute nectar.
The rate of building comb is affected by the availability of nectar. A supply of nectar or 1:1 syrup stimulates comb building, but the bees may build on an “as need” basis when they perceive that nectar is in short supply.