Dave Hackenberg, a beekeeper in Florida, discovered 400 of his over 2,000 beehives had been abandoned during the winter.

It wasn’t that the bees were dead and their bodies were scattered around the hives.

The bees were just gone. Completely.

The year was 2006, and this was the first of many instances of bee die-offs that had beekeepers across the country, including in Tennessee, scratching their heads trying to figure out what was happening to their bees.

Since then, scientists around the world have investigated the causes of this “bee-pocalypse,” trying to figure out the reason for this environmental mystery.

If you’ve been paying attention to the buzz over bees for the last few years, you’re probably familiar with the term colony collapse disorder, or CCD, which has become the generic label for the current bee crisis.

But several researchers, including University of Tennessee apiarist Dr. John Skinner, are not convinced CCD is the best label to use.

“Colony collapse disorder is just a small part of what’s happening to our pollinators,” says Skinner, who prefers the term ‘honeybee decline’ to describe the current bee situation.

“There is no magic bullet,’’ he adds.

Potential culprits include a combination of stressors, including poor bee nutrition, loss of forage lands, parasites, pathogens, lack of genetic diversity and exposure to pesticides.

There is no consensus on exactly what’s killing the bees.

We all need bees

In the United States, the crops pollinated by honeybees are valued at $15 billion annually.

In Tennessee alone, the value of crops benefiting from honeybee pollination exceeds $119 million annually.

But, honeybee decline is currently at its worst. Half the honeybee colonies used to pollinate crops in the United States have collapsed over the past year, according to the USDA.

“We try to get people to understand that bees are very valuable to their existence,” Skinner explains. “We couldn’t have the diets we have without bees. Imagine what an apple would cost if you had to pay someone to get a feather quill or a paintbrush to collect the pollen.”

And there’s this frightening quote from Albert Einstein: “If the bees ever die out, man will follow four years later.”

This is not entirely the case because staple crops like rice and wheat are pollinated by the wind. Yet, food that diversifies our diet and makes eating pleasurable is pollinated by bees and other threatened pollinators like monarch butterflies. So if we lose them, eating will become very dull.

We’re seeing this play out in regions of China where the overuse of pesticides and chemicals have caused a complete bee die-off. Now, it’s up to migrant workers to hand-pollinate the flowers and trees in the fields.

The Ledger’s Amanda Womac, left, and Geoffrey Duesterbeck, right, observe Dr. John Skinner lift out a frame from the hives at the Bee Lab on the University of Tennessee Knoxville campus.

-- Chase Malone | The Ledger

Researchers at the University of Beijing are unsure how many migrant workers it will take to replace the 4 billion bees used to produce a mountain of almonds in one month. No one really knows.

What they do know is that it’s not sustainable agriculture and a solution to this problem needs to be discovered. Fast.

Traveling around

Honeybees are a critical link in agriculture and extremely important to global food production. One out of every three bites of food we eat relies on honeybees for pollination.

With commercial beekeeping here in the United States, thousands of hives are transported around the country during the seasons to pollinate the food consumed all over the world.

Commercial beekeepers usually begin their journey in California in February, using their bees to pollinate the almond tree plantations. By the time they leave California, the bees have helped produce around 700 billion almonds, which is roughly up to 80 percent of the global almond supply.

Their next stop is Washington State for a feast of apples and cherries before moving on to the Dakotas where they produce the bulk of their honey from alfalfa, sunflower and clover nectar.

Other crops pollinated by honeybees include cranberries in Wisconsin, blueberries in Michigan and Maine, squash in Texas and tangerines in Florida.

By November, commercial beekeepers pack up their hives and return to California or other warm climates for winter when the bees take a break from their work.

During the winter, bees feast on their honey and regain their strength for the upcoming pollination season where the cycle begins all over again.

Pollinators, Pests and Pesticides

Like human communities, each beehive has different qualities, strengths and weaknesses, and that makes identifying the root cause of honeybee decline difficult.

“It’s not just one thing. It’s a combo,” Skinner explains. “It’s a cumulative effect of a number of potential problems. Nowadays, it’s more complicated by the fact that each apiarist selects a different colony to test.”

For example, if one apiarist in one community chooses 10 of her hives to test for infestation or disease, each one of the hives are different, so if two are declining, the reason may be different.

One of the most significant causes of honeybee decline is the Varroa mite; a small, parasitic mite that feeds on the bees when they are developing in their cells.

When a queen bee lays an egg, she drops it in an empty honeycomb cell. A worker bee then comes along and seals the egg in the comb with wax to protect it during development.

The deadly parasitic Varroa mite can be seen on the back of this honey bee.

-- Photo Courtesy Of The Usda, Scott Bauer, Photographer

When a mite is sealed in the comb with the egg, it has a buffet of egg, larva and pupa to feed on for up to 24 days, depending on if the egg is a worker bee or drone. When the bee emerges, if it hasn’t already been parasitized in the cell, the mite is released into the hive.

“Once they are out, they look for another cell, but in the meantime, they might get on the back of another bee,” Skinner points out.

The body of a bee is segmented, and mites like to hide on the thorax or abdomen of the bee. Suction discs on the bottom of their feet help them stick to the bee, which is covered with hair.

The mites are tiny to the human eye, so at first glance you may wonder how this little dot can do so much damage. But imagine a tick the size of a pancake on the side of your leg and you get the picture.

The problem is the mites have a nasty habit of killing their host.

“Their original hosts were Asian honeybees,” Skinner says. “We raise European honeybees and our bees have not developed the genetic mechanism that will thwart them yet.”

That’s why Skinner and other apiarist are looking to genetics to solve this particular parasite problem.

“Genetics are one tool we have of creating hygienic bees against the Varroa mite,” he says. “We have worked on developing resistance measurements, including hygienic behavior to develop bees that will discover there’s a problem and remove it.”

The goal is to raise bees who will uncap the cell of their own developing bee, pull out the contaminated larva or pupa and throw it out of the hive. Another genetic experiment is to develop hybrid bees that carry the Asian honeybee trait resistant to the Varroa mite.

Grooming like monkeys?

Skinner and his team are also looking at a trait called grooming behavior.

Primates, such as monkeys, engage in this behavior by grooming the parasites off each other. It’s a familiar image – monkeys sitting on a tree limb picking through each other’s hair and removing, or even eating, the parasites they discover.

“We think we could develop that trait in bees, too,” Skinner says. “We want to create better groomers, as well as hygienic bees, to take advantage of the genetics so we don’t need to use pesticides. That’s an important part of the whole situation.”

Geoffrey Duesterbeck, a UT graduate student working with Skinner, is looking at the pesticide problem – specifically a pesticide called neonicotinoids, a widely-used class of neuro-toxic pesticides.

Neonicotinoids are used to coat seeds such as soybeans, corn and cotton to protect the plant from just about everything when it’s growing in the field. As far as we know, it has very little effect on humans and mammals such as our pets, but for bees, it’s toxic. Even in small amounts.

Both Skinner and Duesterbeck were hesitant to place all the blame on neonicotinoids because each field and each situation is different.

Foliar applications also affect bees that sometimes find themselves in the middle of a pesticide rainstorm if they are unlucky enough to be out collecting nectar from almond trees, for example, when the trucks come around to spray.

“Blanket statements are not going to cut it,” Skinner says. “When you look at the research, it’s all over the place. We don’t have enough information yet to make a decision on neonicotinoids. That’s why we need to do more work.”

More money for research

Luckily for Skinner and Duesterbeck, this is a good time to be involved with bee research. Skinner recently met with a task force in Washington D.C. to discuss the national and global challenges due to pollinator decline.

“I get a chance to see people from agencies you wouldn’t normally think would have an interest in pollinators,” Skinner explains.

The USDA is heavily invested in solving the problem because of the honeybee’s role in food production. Other federal agencies working to get to the bottom of honeybee decline include the U.S. Forest Service, Department of Transportation and Department of Defense.

In May of 2015, the Environment Protection Agency proposed restrictions to protect bees from harmful pesticide exposure. The proposed restrictions target commercial bees used to pollinate large crop plantations and would prohibit applications of most insecticides and some herbicides during bloom.

A number of universities around the country as well as Canada and other nations are also working on the challenge of solving our pollinator problem.

“I hate to say it, but the positive outcome of CCD is more money going into research for bees,” Skinner explains.

“It opened purse strings and made money available to study the problems we should have been studying anyway.”

Bees need warmth

There are more than 40 beekeeper associations in the state engaged in figuring out what’s happening.

Skinner trains extension agents as beekeepers and helps educate local beekeepers about pests, pesticides and colony health in order to help combat pollinator decline. Skinner also surveys commercial and backyard beekeepers across the country.

Providing a diverse food source for the bees is also important to colony health. Bees get protein from the pollen they collect.

When they spend months at a time collecting one or two particular types of pollen, such as on an almond or apple orchard, the diversity in their diet is affected. It would be like eating chicken for breakfast, lunch and dinner for two months straight.

Skinner and his team also encourage beekeepers not to take off too much honey, which is the source of carbohydrates for bees and what they use to keep warm during the winter.

“Last year we had a very cold spell that put a number of bee colonies out of commission simply because they could not maintain warmth in the colony and they died,” he says. “This is a concern because the weather can also affect bees.”

Bee colonies in East Tennessee are doing pretty good so far this year, according to Skinner.

“We just try to get people to understand bees are very valuable to their very existence,” he says. “We couldn’t have the diets we have without bees.”

The issues with pests, pesticides, colony collapse disorder and general pollinator decline is very complicated, but apiarists like Skinner and Duesterbeck are not giving up hope.

“I would say this is the most exciting time in bee research we’ve had because we have been getting enough funding to be able to study everything better,” says Skinner.

But, he cautions, we still have a long way to go.

“We’re somewhere in the middle of the tunnel with this problem,” he adds.

“We still need work because it seems the more we study it the more questions we tend to have because it’s a more complicated picture than just the original discoveries of something we called CCD.”