Bumblebees are increasingly seen as highly beneficial pollinators of many field grown crops. Orchards have typically relied almost exclusively on honeybees for pollination services, however, strong honeybee hives have increasingly been in short supply, possibly due to the impacts of the varroa mite (varroa doesn't affect bumblebees) and other diseases, and the increasing fame of manuka honey. PSA in kiwifruit has made many orchardists nervous of the movements of apiarists, as they too are potential vectors of disease.
Bumblebees have many characteristics that can be of huge benefit to orchardists and other outdoor growers. Bumblebees are active at far lower temperatures than honeybees, and as such are important pollinators of early flowering crops and varieties, and will begin foraging earlier, and work later than honeybees on any given day. Similarly, bumblebees are more robust, and will forage during light rain and on cloudy days. Their large hairy body, and bumbling movements across flowers make them incredibly efficient pollen transferors. Buzz-pollination
is very effective at pollen extraction, particularly in crops such as blueberries
. Bumblebees show high mobility throughout a crop, and can greatly assist cross-pollination. It has been estimated that bumblebees are at least 20 times more efficient at cross-pollination
than honeybees in avocado
Crops (Click on the blue links for more info)
Icons sourced from the Noun Project, click here to see acknowledgements.
Bumblebees work well with honeybees
, and they can easily be employed together. Bumblebees will often pollinate while honeybees are unable to, such as during cool mornings or cloudy/rainy weather. They are very important pollinators of winter or early flowering varieties, and can be a reliable back up plan during prolonged bad spring or early summer weather. The bumblebees will also promote cross-pollination, and can have significant improvement on yields and fruit size.
It is perfectly possible for an orchard to use solely bumblebees for pollination. While the quantity of bumblebees in a hive are tiny compared with that of a honeybee hive, they do many times more work, and consistently transfer higher quantities of pollen to where it needs to be. Orchardists are generally used to the consistent hum of honeybees on the crop, whereas there may be only a few bumblebees working any given tree at any one time. At first it can be very difficult for growers to get accustomed to the lower numbers of working bees, and it can almost feel like no or limited pollination is happening, that is, until the fruits start developing!