Climate change may be preventing bees from carrying out the vital job of pollination by upsetting their life cycles, a study has shown.
Flowering times of mountain lilies in the US appear to be out of sync with their bumble bee pollinators, evidence suggests.
As a result, fewer of the plants are being pollinated and bearing fruit.
The findings point to a phenomenon that may only be local, or could be globally widespread.
Reports of declining populations of bees and other flower-visiting creatures have raised concerns about pollination levels. There are major implications for farming and food supplies: a third of the world's fruits and vegetables would not exist without the help of bees and other pollinators.
"Bee numbers may have declined at our research site, but we suspect that a climate-driven mismatch between the times when flowers open and when bees emerge from hibernation is a more important factor," said biologist James Thomson, from the University of Toronto in Canada.