If all the bumblebees die, what then? Other bees like solitary ones and honeybees are pollinators, but if they died too, we would be relying on species like butterflies and moths to do the job. Bees evolved as vegans in parallel with flowers millions of years ago and they are totally dependent on this relationship. They feed their helpless young entirely on pollen and nectar, unlike butterflies whose larvae are independent, mobile and generally leaf-eaters.
Evolution has taken bumblebees along several paths. Unlike honeybees, their bodies are particularly furry and they create an electrostatic charge as they fly, making pollen stick to them. Their size is helpful because the healthy ones are strong enough to carry large loads of food to their nest. A great advantage of their strength is the ability to push open complicated flowers like Antirrhinum, Salvia, Mint and members of the pea family which are not available as a food source for other insects. Different species of bumbles have different tongue lengths, unlike honeybees, and so they are adapted to pollinate a wide range of flower shapes and sizes.
Buzz-pollination is a method used only by bumblebees, to shake the pollen out of Tomato, Blueberry, Aubergine and some others. The bee grasps a bunch of stamens and vibrates her wings to trigger the release of pollen. They are so good at this that bumblebees have been transported all around the world to provide this essential service for Tomato growers, and UK farmers import more than 65,000 bumblebee nests a year.
The routine pollination Is also performed better by bumblebees because they work in rain, and at lower temperatures than other species. We even have them flying through the spray when we are watering the garden sometimes. Most plants do not grow near a beehive and so they rely on bumbles out in the countryside to pollinate them. The answer to declining bumblebee numbers is not more honeybee hives (they are competitors) but more flowers to help bumblebees to flourish.
Bumblebee colonies are dispersed throughout an area because each fertilised queen establishes her own nest, usually underground, which means that any predator is likely to have a minimal effect on survival of the local population, whereas a hive holding 100,000 individuals above ground is very conspicuous and vulnerable. Furthermore, there is much greater genetic variety among bumblebees where every colony (with a maximum population of 600 individuals) is produced by two different adults, but the mega-colonies of honeybees are almost genetically identical. This means that a disease like Wing Deformity Virus, or Varroa, can destroy huge populations.
Without bumblebees there would be many fruits missing from our tables. Even those like Strawberry which can self-pollinate, produce poor quality goods. Most plants, fruit, flower and vegetable, cannot produce seed without pollination and our diets would be very thin without them. When our field-margins, parks, hedgerows, allotments, gardens and window boxes are bursting with flowers, we can live in the hope that the bumblebees will survive in the long term.
Adrian Doble
Bumblebee Conservation Trust volunteer
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