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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:

x=20+(0.17)x
1-(20/x)=0.17
1-0.17=20/x
0.83x=20
x=20/0.83
x=24.1

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.

Rusty
HoneyBeeSuite

Wednesday wordphile: honey flow

Honey flow is one of those confusing terms, especially to new beekeepers. What is flowing during a honey flow is actually nectar. Technically, it should be called a nectar flow.

A honey flow is simply a period of time when one or more species of nectar-producing flowers is in bloom and actively producing nectar. During these times, honey bees collect the nectar and bring it back to the hive to be processed into honey. A honey flow may or may not coincide with a “pollen flow”–another weird term since pollen isn’t liquid and doesn’t actually flow. Whether the bees are collecting only pollen or only nectar or both depends on what types of flowers are in bloom at any given moment. It will be different in every location.

Signs of a nectar flow in progress include the appearance of snow-white wax in the hives, bees that seem especially intent on coming and going without a lot of dorking around, and a hive that increases in weight daily. Once you develop an “eye” for honey bees, you can often see the distended abdomens of nectar-laden bees.

Rusty

HoneyBeeSuite.com

A morning sip of nectar

Down the hatch. Bumble bee on goldenrod.
Down the hatch. Bumble bee on goldenrod.


 


 

I have one little patch of goldenrod in front of my house, right next to the driveway. I protect it from pickup trucks and lawn mowers all summer long just so I can watch the bumble bees flock to it in late summer.

This year is no exception. The bumble bees are crazy for a daily fix of its nectar. And when the wind blows, the bees go for a wild ride as the goldenrod whips back and forth like a schooner in a storm.

Wednesday wordphile: proboscis

Honey bees have two sets of mouth parts. The mandibles or “jaws” are used for chewing. The proboscis is a straw-like tongue used for sucking liquids and also for tasting.

Although it may look smooth and uniform, the proboscis is actually quite complex, composed of several different parts. You can think of it as a tube within a tube. The outer tube is useful for sucking in large quantities of liquid such as water or honey. For example, honey bees may vacuum up large amounts of honey when they are robbing another hive, when they are preparing to swarm, or when they are exposed to smoke.

The smaller tube inside the larger one is used for collecting tiny amounts of liquid such as that found inside flowers. This tube is equipped with a hairy spoon-like tip that helps to mop up the small drops of nectar. The tip also has taste receptors.

The proboscis is also used for food exchange between honey bees, a process called trophallaxis. Food is transferred from bee to bee during the honey-making process, but trophallaxis is also a method of information exchange.

The extended proboscis is about 6.5 mm (1/4-inch) long, a length needed to reach deep into many different flowers. When not in use the proboscis is folded up and stored in a groove-like structure in the bee’s head.

Rusty

A honey bee cleaning its proboscis.
A honey bee cleaning its proboscis.

© MzePhotos.com, Some Rights Reserved

A rare case of “honey intoxication” in Seattle

An article in today’s Seattle Times reports that three King County residents were recently affected by foodborne toxins. Unfortunately, one came from a sample of local honey.

According to the article a man became ill after eating a portion of honey he had purchased at a local farmer’s market. He reported vomiting and “intestinal difficulties” which began about an hour after consuming the honey. The honey sample was sent to the state department of agriculture, but tests were unable to confirm the presence of a toxin.

However, the man’s symptoms led officials to believe the honey contained grayanotoxin, a material found in rhododendron plants. The condition, also known as “rhododendron poisoning” or “honey intoxication,” is well-documented but rare.

Grayanotoxin is a naturally-occurring neurotoxin found in the nectar of rhododendrons. According to Wikipedia, symptoms include salivation, perspiration, vomiting, dizziness, and low blood pressure. The condition is rarely fatal and usually abates within 24 hours.

In a cruel hit to small honey producers, the author of the Seattle Times piece writes that local honey is much more likely to contain toxic levels of grayanotoxin than honey coming from large commercial producers because commercial producers mix honeys from many sources–a variation on “dilution is the solution to pollution.”

The ABC & XYZ of Bee Culture mentions that both the nectar and pollen of rhododendron are poisonous to bees as well as humans. Although the toxin can kill the bees, it is well diluted with water in the nectar. But as the water is driven from the nectar to produce honey, the grayanotoxin is concentrated to poisonous levels.

I didn’t find any references to how frequently honey intoxication occurs but the numbers must be low. The Puget Sound area is overrun with rhododendrons–in fact it is the Washington state flower–but few cases of poisoning are reported. My own property is loaded with both honey bees and rhododendrons but I have never seen a honey bee on a rhododendron flower. These observations lead me to believe that rhododendron is not a preferred forage for honey bees and they probably collect it only in rare circumstances when other more favorable blooms are not available.

If you are interested in foodborne toxins, the Seattle Times article is interesting. Besides honey intoxication you can read about toxic squash syndrome and combroid fish poisoning. So, what’s for dinner?

Rusty

Rhododendron ten feet from a busy hive
Rhododendron ten feet from a busy hive