City buzz makes bees stronger

BUMBLEBEES in cities are bigger and more hard-working than those living in the countryside, according to a study.

Scientists found they were about 4 per cent larger than their country cousins and reckon this is because they have to work harder to find food, travelling across roads – which break up the gardens, cemeteries, parks and other green spaces where they seek the next patch of flowers.

Larger bees may be better able to face city commutes to find pollen, as they are superior at flying long distances, with larger flight muscles.

They are also less easy targets for predators and appear better at spotting flowers and recalling their location. The study compared 931 bees from green spaces close to nine German cities with 898 bees from rural areas with few roads and lots of farmland and forests.

The bees the researchers looked at were red-tailed bumblebees, common carder bees and buff-tailed bumblebees – one of the most common species in the UK.

They measured the size of bumblebees based on the distance between their wings – and found they tend to be bigger in cities.

All three species were larger when there were several roads within a 270 yard radius, suggesting they had to be bulkier to fly across them to reach other flowers. ‘Larger bumblebees can see better, have larger brains and better memories,’ said biologist Dr Antonella Soro of Martin Luther University in Halle-Wittenberg, whose study was published in the journal Evolutionary Applications.

‘They can also travel greater distances, which is an advantage in a fragmented landscape such as the urban one.’

Bees in urban areas also appeared to be more productive, based on how well they pollinated red clover plants examined for the study. Previous evidence has shown bigger bees are busier, visiting more flowers in a day than their smaller counterparts.

Bumblebees were smaller when they lived in warmer temperatures, the study found, but the heat from cities did not appear to add to this effect.