WARMER springs are causing British bees to come out of hibernation earlier, threatening the pollination of crops such as apples and pears, according to a new study.
The University of Reading research found that for every one degree Celsius rise in temperature caused by climate change, wild bees, such as bumblebees, emerge from their nests 6.5 days earlier than average.
As bees emerge closer to the start of the year, they may lose sync with the plants on which they depend, meaning there may be less food for them to consume. Bees may not have the energy to pollinate crops effectively, or may miss crop blossom completely.
PhD researcher Chris Wyver, of the University of Reading’s School of Agriculture, Policy and Development, led the study, which is published today in Ecology and Evolution.
He said: “Rising temperatures are making life tougher for bees. Warmer conditions mean bees emerge from hibernation earlier, but there may not be enough food to provide energy for them when they start buzzing about.
“Matching wake-up dates with plant flowering is vital for newly emerged bees because they need to find pollen and nectar to increase their chances of survival and produce offspring. A mismatch means bees cannot pollinate effectively.
“Less natural pollination could lead to farmers needing to use managed honeybees, meaning greater costs, which may be passed on to consumers. We could see even more expensive apples, pears and vegetables in supermarkets as a result.”
The study examined 88 different species of wild bees over a period of 40 years, using more than 350,000 individual recordings that showed shifts in emergence dates, both over time and in relation to temperature.
Data showed that some bees emerge earlier than others as different species of bee respond differently to the changing temperature. On average, the 88 species are emerging four days earlier per decade.
With winters projected to be between 1-4.5 degrees Celsius warmer and up to 30% wetter by 2070, according to the Met Office, spring is likely to continue to start earlier and bees will continue to become active earlier in the year.
The shift in bee emergence will also have a greater effect on plants that are heavily dependent on pollination, such as apple trees, which may not be ready to flower by the time hibernation ends.
Understanding how climate change affects when flowers bloom on crops is also important because it can affect how well they are pollinated.
Chris and his colleagues at the university and Oracle for Research have set up FruitWatch, a project that encourages people to report when fruit trees in their gardens, nearby parks or allotments, start to flower.
More than 6,500 submissions have been received in two years, and they will help the research team develop a greater understanding of the role climate change has on the flowering of fruit trees and pollination from bees.
