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Science and HoneyBeeSuite

In the past couple of years I’ve spoken to a number of groups about bees, bee habitat, and pesticides. But on Thursday night I was once again invited to present my master’s thesis to a batch of graduate students in the Master of Environmental Studies program at The Evergreen State College.

These students are by far my favorite group to speak to. They get it. They are engaged. Although most of them have no knowledge of bees whatsoever, they quickly grasp the problems associated with bees, pesticides, and the regulatory shortcomings that allow the excessive use of toxic chemicals around bees and bee-pollinated plants.

My thesis is a literature review that explores the world of larval bees and develops the argument that larvae are highly susceptible to the systemic pesticides found in pollen—pollen that has been brought into the hive for the express purpose of raising the young. The paper looks at the way larvae are fed and the possibility that the larvae consume metabolites of the original compounds—chemicals that are often much more toxic than the original products. It also discusses pollen contaminated by preparations (fungicides and herbicides) normally considered safe for adult bees, but which are clearly detrimental to the soft-bodied larval form.

Although the material is highly technical, the MES students follow it with an eagerness that is truly gratifying. After this last session, dozens of questions awaited me at the end of my presentation and I answered one after another until the faculty members finally had to cut them short. The persistent ones gathered around the podium with more questions while I packed my computer and donned my coat.

When I first began writing HoneyBeeSuite, I was warned that too much technical information would turn readers away. But as with the presentations, I find that people really do want to know and want to learn. I try to parcel out the technical stuff in easy to understand bits and pieces, but I never shy away from it. Thursday’s successful talk gave me renewed interest in pursuing even more of these difficult subjects on HoneyBeeSuite.

So while I plan to continue my commentary on day-to-day beekeeping interspersed with attempts at humor, memoir, and the occasional rant, you can expect to see a bit more of the truly scientific. The more we understand the consequences of our environmental actions, the better the choices we can make in the future—for our bees, our food supply, and our planet.

Rusty

HoneyBeeSuite.com

Wednesday wordphile: grafting

Grafting is the process of transferring young larvae from worker cells into special cups used for raising queens. Larvae used for grafting are selected from the offspring of a “breeder” queen, that is, a queen whose genetics appeal to the beekeeper.

Larvae used for grafting must be between 12 and 24 hours old. These larvae are about the size of the egg they hatched from and are extremely delicate. They must be transferred using a special tool aptly called a “grafting tool.” Grafting tools range from simple implements, such as modified toothpicks or artist paint brushes, to specially manufactured tools with retractable springs and mini-scoops.

Grafting requires a lot of practice and a steady hand. Beekeepers often hone their skills on random larvae before their first attempts at queen rearing.

Too much moisture in the hive

Yesterday I when I pulled the drone frames out of the hives, I discovered the most populous hives were dripping wet under the cover. I had tried to prevent this by using upper entrances, but apparently the one-inch holes I installed were not big enough to keep the interior dry in spring.

Part of this problem is due to the weather; it has been rainy and cool for the last several weeks so it’s hard to keep anything dry. It’s also partly due to the populations in the hives—lots of bees mean lots of respiration and also lots of nectar collection. Everything, it seems, gives off moisture.

Moisture in the hive is not a good thing. Disease organisms, fungi, and molds thrive in moist environments and, in cold weather, water droplets can drip down on the bees and chill the brood. Proper ventilation is important for bee colonies year round. Bees can do really well in cold temperatures, but cold and wet is a different story.

I manage to keep my hives dry all winter with one lower and one upper entrance, but this time of year when the populations are huge and nights are still cold, it’s a bigger problem. So yesterday I removed the inner covers and replaced them with screen covers that have half-inch shims along the short ends. The shims prevent the outer cover from laying flat against the screen. The damp air can flow from the hive, up through the screen, and out the half-inch space on either side.

These screens greatly improve airflow but prevent insects—such as foreign bees or wasps—from coming in through the top.

After that was all done, I fed drone brood to the chickens—the ultimate in recycling! The nurse bees eat the pollen so they can secrete royal jelly and feed the larvae, and the chickens eat the larvae so they can lay the eggs which we can eat for breakfast—along with toast and honey, of course. What a system.

Rusty

This 11-year-old Araucana hen thrives on drone brood.
This 11-year-old Araucana hen thrives on drone brood.

Honey bee eggs in the brood nest

Once the brood comb is prepared, the queen lays one egg in each cell. Estimates vary widely as to how many eggs a queen can lay, but 1500-2000 per day is a reasonable assumption. Over the course of one spring and summer season, the queen probably reaches a maximum of about 200,000 eggs.

When first laid the eggs are about 1/16 inch long (1.6 mm) and a pearly translucent white. Oddly, they stand on end in the cell. Gradually, within the first day, they tip to one side and lie prone at the base of the cell. After about three days, the chorion—the membrane coating the egg—dissolves and the new larva is exposed.

Honey bees keep the brood nest at a constant temperature that ranges from about 91-97° F (33-36° C). This phenomenon is unique in the insect world and requires large populations. If the population isn’t large enough to care for all the brood and keep them warm, the queen will slow the rate of egg laying, and the workers may eat some of the eggs.

The excellent photograph below shows the eggs standing upright in the cells. In the upper left you can see larvae floating in pools of milky-colored royal jelly.

Rusty

Eggs and larvae in the brood nest. Photo by Wausberg
Eggs and larvae in the brood nest. Photo by Wausberg

Water collection by honey bees

Water has several uses in a honey bee hive. During certain times of the year foragers find a source of water, fill their crops, and ferry it home. The number of bees foraging for water depends on the needs of the colony. If the in-hive workers accept the water quickly from the foragers, the foraging bees sense that the need is still high, and they will go back for another load. If the in-hive workers are slow about “unloading” the water, the foragers sense that the need for water has lessened and fewer bees will return for more.

Bees find water in a number of places including damp rocks, branches, muddy puddles, pond edges, and drops adhering to vegetation. They swallow the water and store it in their crops before flying home. The water is transferred to the waiting in-hive workers through the process of trophallaxis—the direct transfer from one bee to another.

Bees rarely store water, but bring it in as needed. In the heat of summer it is used for evaporative cooling. The water is spread in a thin film atop sealed brood or on the rims of cells containing larvae and eggs. The in-hive workers then fan vigorously, setting up air currents which evaporate the water and cool the interior of the hive. The process is similar to the human-designed air conditioner.

Nurse bees, who feed the developing larvae, also have a high demand for water. The nurses consume large amounts of pollen, nectar, and water so that their hypopharyngeal glands can produce the jelly that is used to feed the larvae, and to a lesser extent, other bees in the hive.

A third use for water occurs in the winter. Stored honey—especially honey high in glucose—tends to crystallize as it dries. Bees need water to dilute the crystals back into liquid before they can eat it. The same occurs if a beekeeper feeds crystalline sugar to bees as a winter supplement: the bees need to dissolve the crystals before they can eat the sugar.

Urban beekeepers face a problem when their bees select the neighbors’ swimming pools, bird baths, or hummingbird feeders as a water source. Although this occasionally happens, the bees’ need for additional water is less during nectar flows because the nectar contains a high percentage of water. Urban beekeepers can provide a source of water if they wish. Bees seem to prefer water that has some growth in it—such as green slime—rather than perfectly clean water. Some scientists speculate that the reason is simply that the bees can smell it and recognize it as a water source. Chlorinated pools were scarce during the last 80 million years, so bees didn’t evolve to recognize the odor.

Another problem with water collection occurs in agricultural areas where plants are treated with systemic insecticides. Bees collecting water from guttation drops—drops of water that naturally seep from the tips of stems and leaves—can be poisoned. Worse, sublethal doses of pesticide can be carried back to the hive and fed to the developing larvae by way of the nurses. Researchers are currently trying to determine the type and frequency of damage this may cause to honey bee colonies.

Rusty