http://www.thehindu.com/sci-tech/article2119939.ece

Global warming has led to many plants blooming ever earlier and also before honey bees emerge from hibernation, leading to fears of a long-term decline in pollination.

A combined research group centred at Munich's Technical University (TU) has carried out a study into how bees are dealing with the change in global temperatures.

"We have increasingly noticed an ever growing difference between temperature and flight activity," said bee expert Juergen Tautz from Wuerzburg University.

Research has shown that the European spring is being pushed forward by 2.5 days every 10 years but it is still not known how exactly the earlier rise in temperatures is affecting the behaviour of bees.

TU doctorate student Raimund Henneken has been investigating how bees are reacting to the higher temperatures. "Bees are directly affected by ambient temperatures and indirectly dependent on climate and the flowering of plants," he said.

"Accordingly, it is important to observe year by year the behaviour of bee populations early in the spring season. This is the way to see later how the behaviour of bees is affected by climate change." The project concentrates on swarming, the natural means of reproduction of honey bee colonies. In order for swarming to occur the weather has to be mild for several weeks when about 60 per cent of the worker bees leave the original hive location with the old queen.

Insects also have to be fit and healthy for swarming to take place and the event usually occurs on a warm and sunny day. Mr. Henneken explains how beekeepers have often been called to remove thousands of bees hanging off tree branches in and around Munich.

"If they weren't captured, they would have moved on within two or three days," he explains.

The information about swarming is essential to Mr. Henneken's research. He collects the data courtesy of help from beekeepers, local fire services and police who generally receive calls from the public about swarming bees in the area.

Mr. Henneken notes the GPS location and weather data for each swarm and has even set up a web text service for people to log the location of swarms.

"The response to date has been very good. So far over 1,000 swarms have been registered, especially in the federal states of Bavaria, Baden-Wuerttemberg and North Rhine Westphalia," he says.

Mr. Henneken has received less information from eastern Germany and the coastal regions. "It has been particularly difficult to inform beekeepers in very rural areas about the project," he explains.

A lot of beekeepers in these regions are pensioners without mobile phones or internet access. Furthermore, the swarming of bees is less likely to be noticed and registered in sparsely populated areas.

However, any successful research needs an equal amount of results from all over Germany. "The primary objective of the project is to describe the swarming behaviour of bees in detail," explains the scientist.

After several years it will then be possible to assess the impact of climate change on the behaviour of bees. Mr. Henneken has already noticed a strong correlation between temperature and swarming activity.

Bee expert Dr. Tautz expects the research to change people's understanding of how honey bees behave. Recently, Mr. Henneken linked his research with that of American bee researcher Thomas Seeley, who in the 1970s also engaged in detailed research of bee swarming but was unable to avail himself of the advantages of modern technology.