Honeybees ‘entomb’ pollen to protect against pesticides
By sealing up cells full of contaminated pollen, bees appear to be attempting to protect the rest of the hive.
Honeybees are taking emergency measures to protect their hives from pesticides, in an extraordinary example of the natural world adapting swiftly to our depredations, according to a prominent bee expert.
Scientists have found numerous examples of a new phenomenon –bees “entombing” or sealing up hive cells full of pollen to put them out of use, and protect the rest of the hive from their contents. The pollen stored in the sealed-up cells has been found to contain dramatically higher levels of pesticides and other potentially harmful chemicals than the pollen stored in neighboring cells, which is used to feed growing young bees.
“This is a novel finding, and very striking. The implication is that the bees are sensing [pesticides] and actually sealing it off. They are recognizing that something is wrong with the pollen and encapsulating it,” said Jeff Pettis, an entomologist with the US Department of Agriculture. “Bees would not normally seal off pollen.”
But the bees’ last-ditch efforts to save themselves appear to be unsuccessful – the entombing behaviour is found in many hives that subsequently die off, according to Pettis. “The presence of entombing is the biggest single predictor of colony loss. It’s a defence mechanism that has failed.” These colonies were likely to already be in trouble, and their death could be attributed to a mix of factors in addition to pesticides, he added…
Bees naturally collect from plants a substance known as propolis, a sort of sticky resin with natural anti-bacterial and anti-fungal qualities. It is used by bees to line the walls of their hives, and to seal off unwanted or dangerous substances – for instance, mice that find their way into hives and die are often found covered in propolis. This is the substance bees are using to entomb the cells.