Better Buzz

As World Worries About Hive Deaths, Scientists Breed Stronger Bees

I'm a king bee baby, buzzing around your hive. Source: DPA
I'm a king bee, baby, buzzing around your hive.
  • Why it matters

    Why it matters

    A surge in bee deaths in recent years known as “colony collapse disorder” could threaten to disrupt global agriculture, which is highly dependent on bees for crop pollination.

  • Facts


    • “Colony collapse disorder” is thought to be caused by disease, parasites, monoculture, pesticides and the loss of genetic diversity of the bees.
    • Every bee population in Germany has been affected by the Varroa mite.
    • Berlin scientists have bred bees that can signal to others they are infested and need to be groomed.
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The entrance to the Bee Research Institute Hohen Neuendorf near Berlin is littered with small cadavers. Even in the halls of the laboratory there are dead bees. It would be easy to think of this as a case of colony collapse disorder, which has sparked alarm around the world.

“No, here everything is just as it should be,” says the Institute’s director, Kaspar Bienefeld.

Worker bees live for only 30 to 35 days in the summer. And since the Institute houses many dozens of hives, the number of dead insects can be very large.

Farmers sow seeds and plant crops, bees pollinate the blossoms and in doing so ensure a rich harvest of cucumbers, apples, and onions. For centuries this interaction has worked between people and nature. But now there are problems everywhere. In the middle of the 1990’s suddenly all of the bees were gone from the apple growing region of China, near the city of Chengdu. Since then a giant band of migratory workers pollinate the blossoms by hand, going with brushes from tree to tree.

The U.S. Environmental Protection Agency has expressed concern since 2006 of the collapse of many honeybee populations. The reasons are reportedly sickness, monoculture, pesticides and the loss of genetic diversity. But transporting the bees over great distances also causes stress and further weakens the bees. It is a vicious circle. The lack of pollinators makes the situation more precarious.

It is normal that in winter many insects die, but in past years, and as recently as 2012, in Germany one-third of the bees died. “That is unacceptable,” says Mr. Bienefeld. The number of bees in Germany has declined since 1995, from almost one million to a low of 600,000 in 2009.

That’s partly because the Varroa mite has affected every bee population in Germany. The parasites develop in the brood, suck blood and damage the bees so that they creep out of the covered cells in the honeycomb with crippled wings.They are also more prone to an abundance of other diseases that have since broken out in the hive.

But even more threatened than the honeybees are the wild bees and bumblebees. Since they are not kept and bred by humans, they are at the mercy of changing environmental conditions. Their genetic diversity has been rapidly shrinking for years, especially in those regions with pronounced monocultures, such as in the corn-growing region in the German state of Brandenburg. Corn is pollinated by the wind, and offers the bees no nourishment.

Excuse me, might you check me for mites? Source: DPA
Excuse me, might you check me for mites? Source: DPA


“The primary reason for the death of the bees is the combination of Varroa mites, the fungal disease Nosema and various secondary infections with bee viruses, but also the growing stress on the environment through pesticides,”says Peter Rosenkranz of the Apicultural State Institute at the University of Hohenheim. His team was able to find 20 to 30 different pesticides in the pollen gathered from bees. These chemicals don’t directly kill the insects, but they weaken them and make them more susceptible to diseases.

Last fall, the European Commission prohibited the use of pesticides from the class of Neonicotinoides, of which only a few nanograms could be fatal for a bee. The work of different researchers has suggested that this chemical could impair the bee’s orientation. Uwe Greggers, a neurobiologist at the Free University in Berlin, observed through experiments how the dance of some bees changed with even just small doses of the pesticide.

For ten years, researchers at the Bee Research Institute Hohen Neuendorf have been breeding Varroa tolerant bees. Domestic honeybees have two ways to protect themselves against the mites: if they are affected, they perform a dance in the hive. They quickly wiggle their abdomens back and forth. Not all of the bees understand the signal, so the bee dances again for a minute in front of them. Then a worker bee comes and climbs on top of the infected bee. Thankful, the bee spreads its wings to be carefully cleaned. The mite has no chance.

Mr. Bienefeld is sure that bee mortality, which many people consider a harbinger of the end of the world, can be stopped and contained.

Some bees apparently can, despite the wax cap, also smell which larvae have parasites. They open the nest lid, remove the infected offspring and throw it out of the hive. Among thousands of bees, there are often fewer than a handful that are Varroa aware.” In the 1990s, Mr. Bienefeld’s team developed ways to sort out these bees and breed them. The scientists use nail polish to attach tiny metal plates to the insects. These plates are round or have various shapes, have a number between 1 and 9 placed at 12 o’clock, 3 o’clock, 6 o’clock or 9 o’clock. By using these numbers on the backs of bees, the researchers are able to distinguish between more than 2,000 bees.

It is not simple to breed bees. Normally, only the queen bee lays the eggs for the entire colony. “We use a trick, and we are the first ones to do this in the world,” said Mr. Bienefeld. If they let the worker bees live without the queen for three to four weeks, their ovaries develop and they can lay eggs. “That doesn’t always work, of course,”said Mr. Bienefeld. “But sometimes it does. And drones develop out of the unfertilized eggs. That is how the best bees become the fathers of the next generation.”

At the same time, the team is looking at which bees were the mothers of the most disease-resistant offspring. These insects are chosen by the researchers to breed. The best insects must be bred with the best progeny so that they continue to enrich the genetic characteristics for Varroa protection. “The populations we have are largely more resistant to mites than other honeybees,” Mr. Bienefeld said. But the parasites can still be dangerous to them. “We haven’t finished yet.”

Molecular biology methods could help accelerate breeding by 2015. Mr. Bienefeld’s team spotted about 20 places in the bees’ genotype that accompany an increased Varroa resistance. A little bit of bee blood for a genetic test could replace the time-consuming practice of putting tiny plates on the bees. Soon, beekeepers should be able to buy the test in the form of a chip.

Today, the Institute is giving its robust bees to breeders, so that they have more resistant insects in their hives. “When we test the bees from beekeepers, we see the success,” said Mr. Bienefeld. “For about 10 years, the ability to protect against Varroa has increased.”

He is sure that bee mortality, which many people consider a harbinger of the end of the world, can be stopped and contained.

This story first appeared in Der Tagesspiegel. It was translated by Mary Beth Warner. To contact the author:

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