Buff-tailed bumblebees can detect and avoid nectar contaminated with metals such as copper or cadmium. Photo: ImageSelect
When offspring are involved, bumblebees prefer clean food.
Bumblebees can detect contaminated food. When a better alternative is available, they avoid nectar containing metals. When it comes to offspring, they always choose clean food. These are the findings of laboratory experiments by a Belgian-British research team (Proceedings of the Royal Society B, 3 September).
Worker bees (Bombus terrestris) given a choice between clean sugar water and sugar water containing copper or cadmium prefer the clean option. This changes when the food quality is lower. If the sugar concentration in the clean food is lower, the bumblebees opt for the contaminated but sweeter food. When larvae are present, however, that choice changes. In that case, the workers always choose clean food, even when the sugar concentration is low.
This presumably protects the young, which are considerably more vulnerable. They express fewer genes that help break down toxins and are therefore less able to process metals. For adult bumblebees, the trade-off appears to be different, with energy intake taking priority. The fact that bumblebees are capable of making the right choice themselves when a good alternative is available could be valuable information for conservationists seeking to support bumblebees in polluted areas, the researchers suggest.