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.
“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.