Wild Bees Emerge From Nests Earlier as Temperatures Rise, Causing ‘Mismatch’ With Flowering Plants, Study Finds

Bees need flowers for food, and flowers need bees to pollinate them, so it is of vital importance that bees emerge from their nests at the same time as plants are flowering each year.

A new study led by researchers from the UK’s University of Reading has found that human-induced climate change is causing warmer springs that are rousing British bees from their nests earlier with each degree of global heating.

This could mean fewer flowering plants available when the bees wake up, meaning less food and lower reproduction rates, a press release from the university said. The result could be that crops like pears and apples end up not getting pollinated.

“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,” said Chris Wyver, a Ph.D. researcher with the University of Reading’s School of Agriculture, Policy and Development and lead author of the study, in the press release. “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.”

The study, “Climate-driven phenological shifts in emergence dates of British bees,” was published in the journal Ecology and Evolution.

The research team found that for every degree Celsius temperature increase caused by climate change, bumblebees and other wild bees came out of their nests an average of 6.5 days earlier.

The rhythm between bees and flowers is so important that its disruption could mean bees not having enough food or energy to effectively pollinate, or may mean they miss the blossoming of crops entirely.

“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,” Wyver said in the press release.

The researchers looked at 88 wild bee species over four decades, recording changes in dates of emergence related to time and temperature. The 350,000 recordings showed that some bees came out of their nests earlier than others, since different species respond differently to temperature fluctuations. The data showed that the species were emerging an average of four days earlier every 10 years.

According to the UK’s Met Office, by 2070 winters are predicted to be from one to 4.5 degrees Celsius warmer and as much as 30 percent wetter, which means spring will likely keep starting earlier and bees will emerge sooner.

FruitWatch is a project that encourages individuals to report the flowering dates of their fruit trees. It was set up by scientists from the University of Reading and the Oracle for Research Blog and will assist them in better understanding how climate change affects flowering and pollination. In two years, more than 6,500 submissions have been received for the project.

“Without insect pollination, we risk a severe reduction in the quality and quantity of fruit crops. Thanks to Oracle for Research, we can now engage citizens to help us understand the relationships between fruit trees and pollinators to safeguard production into the future,” Wyver said, according to the Oracle for Research Blog.