British biologists have found that bees and bumblebees prefer diluted nectar, since thick syrup is much more difficult to "unload" into the honeycomb with future honey after returning to the hive. The article was published by the Journal of the Royal Society Interface.
“Bumblebees have to maintain a balance between the nutritional value of nectar and how quickly you can drink it. As we know, thick and sticky syrup is extremely difficult to drink, but imagine that you still had to spit it back through a straw. Bees and bumblebees have to consider how they not only receive a lot of energy, but also spend on food, - commented on the study one of its authors, a biologist from the University of Cambridge (UK) Jonathan Pattrick.
Depending on the structure of their oral apparatus and the history of evolution, animals and insects collect nectar in two ways. On the one hand, butterflies, hummingbirds and ants simply suck in the sweet liquid without resorting to any tricks. In principle, they cannot drink thicker nectar because of its high viscosity.
On the other hand, bats, bumblebees and bees take advantage of the thick nectar sticking to their tongues. Thanks to this, they can quickly immerse it in liquid and take it back out, repeating the operation until they are full.
Previously, biomathematicians measured how quickly they both collect nectar, and found that for both groups there is a certain ideal concentration of sugar that makes its absorption as fast as possible. For butterflies and hummingbirds, this figure is 33%, and for bees and bumblebees - 52%.
Bees and syrup
Guided by this idea, Pattrick and his colleagues studied what nectar the common British bumblebees (Bombus terrestris) prefer to drink, and also tested how the use of syrup of different concentrations affected the life of these insects.
In particular, biologists were interested not only in how quickly bees and bumblebees can drink thick nectar, but also how quickly they get rid of it when they return to the hive. To answer this question, scientists prepared several versions of artificial nectar, diluting sugar syrup with different amounts of water, and also assembled a kind of artificial hive, where the insect could "donate" its prey.
Observing the movements of bumblebees between artificial "flowers" with this nectar and the colony, as well as constantly weighing insects, scientists have discovered several interesting patterns, the existence of which no one previously suspected.
In particular, bumblebees preferred to drink nectar not with the "optimal" 52% sugar, but its diluted version with 33% carbohydrates. This, as further observations showed, was due to the fact that it was very difficult for bumblebees to "unload" nectar from themselves. In addition, they spent significantly more energy on the entire procedure for collecting and delivering syrup to the hive.
"When the nectar was quite liquid, the bumblebee could spit it out in just a few seconds and start flying back to the place of its collection. If it was thick, the insect had to strain very hard, spending more than a minute on this procedure," explained Pattrick.
All this, according to scientists, well explains why all existing flowers produce nectar, the concentration of sugar in which is very far from the supposedly "ideal" 52%. Scientists note that this feature of pollinators should be taken into account when creating new varieties of cultivated plants, as well as when restoring populations of bees and bumblebees, whose numbers have sharply declined in recent years.