Researchers from the University of Exeter in England studied the impact of droughts on flower-producing plants. Plants in areas with prolonged periods of drought produced about half as many flowers than usual.
“The plants we examined responded to drought in various ways, from producing fewer flowers to producing flowers that contained no nectar,” said University of Exeter researcher Ben Phillips.
The production of flowers is critical to bees and other pollinators that visit for the nectar and pollen they need to live.
The gradual decline of pollinator food sources will impact not only bees but other insects and animals in their habitats.
“Not only are these insects vital as pollinators of crops and wild plants, but they also provide food for many birds and mammals,” said University of Exeter researcher Dr Ros Shaw.
With climate change, droughts are expected to become more common and more intense in many parts of the world, according to the study.
Bees are already under pressure from a variety of threats including habitat loss, synthetic pesticides, the spread of various diseases and the introduction of invasive species in their habitats.
In late March, Exeter biologists and entomologists moved closer to developing pest-control substances that aren’t deadly to bees by identifying the pollinator enzymes that determine how sensitive honeybees and bumblebees are to a certain pesticide.
Researchers implemented the study in Wiltshire, a rural area of southern England. The region features large fields of chalk grassland, which they said is an important habitat for pollinator species in the United Kingdom.
Chalk grasslands are the result of forest clearing. The thin soils are rich with lime sourced from underlying chalk or limestone rocks. Plants that spring from these soils typically don’t grow in other soils but tend to attract many pollinators.
Researchers studied three plant species including meadow vetchling, common sainfoin and selfheal.
Previous studies of the impacts of drought on flowers and bees have looked at individual species, often in the laboratory. Dr Ellen Fry, a researcher at the University of Manchester, set up the experiment in rain shelters to examine the effects on “real communities of plant species” existing on the chalk grassland plains.
“The level of drought that we looked at was calculated to be a rare event,” Fry said. “With climate change, such droughts are expected to become much more common.”
Researchers said the study may demonstrate the future potential for smaller numbers of bees and other pollinators to survive in chalk grassland. However, they said the results are likely to be broadly applicable to other regions and habitats.
The research was carried out by the University of Exeter in collaboration with the University of Manchester and the Centre for Ecology and Hydrology.