Bees stung by 'climate change-linked' early pollination

Climate change could be affecting pollination by disrupting the synchronized timing of flower opening and bee emergence from hibernation, suggests new US-based research.

Declining numbers of bees and other pollinators have been causing growing concern in recent years, as scientists fear that decreased pollination could have major impacts on world food supplies.

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.

Previous studies have focused on pollinators and have linked falling populations to the use of pesticides, habitat loss and disease.

However, a 17-year analysis (one of the longest investigations of its kind ever conducted) of the glacier lily, Erythronium grandiflorum, (left) in the Rocky Mountains of Colorado by scientists from the University of Toronto, suggests other factors may be at play. The study revealed a long-term decline in pollination, which was particularly pronounced earlier in the season.

Flowering times of the 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.

Study author James Thomson said while bee numbers had declined at their research site he suspected that a 'climate-driven mismatch between the times when flowers open and when bees emerge from hibernation is a more important factor'. (Right: wildflowers in early bloom)

Thomson found in his study a progressive decline in pollination over the years which was most pronounced early in the flowering season

'Early in the year, when bumble bee queens are still hibernating, the fruiting rates are especially low,' he said. 'This is sobering because it suggests that pollination is vulnerable even in a relatively pristine environment that is free of pesticides and human disturbance but still subject to climate change.'

Despite the findings, other experts remained cautious about the influence of climate change on bee pollination. Francis Ratnieks, professor of apiculture at the University of Sussex, said the downward trend of pollination observed in the study was not strong enough to extrapolate to any wider issues.

'Who knows the degree to which [this] affects the long term viability of the population?' he said. The study also only looked at one plant species, he added.

The Bumblebee Conservation Trust said the most significant factors driving the decline in pollinators were still unclear.

'It is probably a combination of climate change, habitat loss, pesticide use and disease. Unless we act swiftly, these declines threaten both human wellbeing and the survival of natural ecosystems as we know them,' said director Dave Goulson.

Study author Thomson admitted the evidence from the study was still weak but said the results were a warning that the phenomenon 'might be widespread and needs more attention'.

'It certainly suggests that people who have warned about the possible climate-change consequence of dislocated timing between interacting species have made a reasonable argument,' he added.

Source:
The Guardian, "Bees stung by 'climate change-linked' early pollination", accessed September 8, 2010
WAToday,"Climate Change affecting Bees", accessed September 8, 2010