After hibernation, bumblebees wake up very hungry, but due to the vagaries of the weather, the plants may not yet have flowers with nectar. In such conditions, instead of starving and risking death, these intelligent insects resort to physical stimulation of plant flowering. Researchers at ETH in Zurich, Switzerland have studied this process in detail and come to unexpected conclusions.
Observing hungry bumblebees, scientists saw how they, with the help of mandibles and paws, make a couple of small through holes in a plant leaf in a second. They do not need the leaf itself, they do not spoil it and do not carry it to the nest, as a building material, they just leave it on the plant. The hungrier the bumblebee, the faster and more holes it makes.
The scientists took two control plants, black mustard and tomato. Some of the plants were allowed to be processed by bumblebees, the other scientists were manually perforating, plus they left the control group. In comparison, tomato with bumblebee bites began to bloom 30 days earlier, and mustard 17 days earlier. Man-made holes accelerated the flowering of tomato by 5 days, and mustard by 8 days.
Probably, bumblebees, during a bite, transmit a certain special chemical signal to plants, without which stimulation is not so effective. But there is another theory according to which if the bumblebees die of hunger, they will not be able to pollinate the flowers, and this is already a threat to the plants themselves. And therefore, they react to holes in the leaves as a command for urgent action in common with the symbiont's interests. It is not known how such an unusual natural device originated, but its existence shows how flexible and complex the mechanism of evolution can be.