Scientists from Switzerland's Department of Environmental Systems Sciences found bumblebee's secret to accelerating flower production when there is pollen shortage: bite the plant's leaves.
According to their research article in Science, three species of bumblebees use their mouthparts in a characteristic way to damage mustard and tomato leaves leading to earlier flowering by as much as 30 days. This behavior was more evident during irregular seasonal flowering. Bumblebees rely on flower protein as a major protein source for raising their young during early spring.
The researchers tried to replicate the technique by inducing damage to the leaves, but flowering time did not change. This suggests that the bees use a specific method in stimulating earlier flowering.

[science.sciencemag.org]