What bees and plants get along, everyone knows: in the process known as pollination, bees fly from flower to flower to feed on pollen, transferring reproductive cells from one plant to another. But something new has just been discovered about the process: bees have a trick for when there are few flowers in the environment. A study by Swiss researchers found that bees of the genus Bombus They “nibble” on leaves of plants that have not yet given flowers, which makes the flowering process happen faster than normal.
It all started when researchers at the Federal Institute of Technology in Zurich observed the behavior of bees in laboratory greenhouses. They realized that the insects often made small perforations in the leaves of the plants, but did not appear to be feeding on them. The scientists also realized that the behavior was more frequent in colonies with less access to food, which led the team to question whether there was any relationship with the pollen.
Previous studies have already shown that a variety of environmental stressors, such as disease or periods of drought, can lead to the appearance of flowers more quickly in some species, which led the team to theorize whether it could be behind the behavior of bees. To test, the team prepared three greenhouses with tomato and black mustard plants. In one of them, the plants had contact with purposefully hungry bees, who made small perforations in their leaves; in the second greenhouse, used as a control, flowering happened without any interference; and, in the third, the researchers themselves made small holes in the plants with needles and other equipment to simulate the perforations made by bees.
The results, published in the journal Science, were shocking: plants that had been slightly damaged by bees bloomed an average of 16 days earlier compared to the control group in the case of black mustard, and up to a month earlier in the case of tomatoes. That is, the perforations of the bees really seem to lead to a faster flowering in these species.
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But what intrigued the researchers the most were the plants in the third group (the ones they had punctured themselves). In this case, the plants also gave flowers before the control group, but the difference was much smaller: only 5 to 8 days before. It is not yet clear why: it may be that, as much as humans try to imitate the perforations of bees, the end result is never 100% the same. Or it may be that the bees release some kind of chemical substance in the process that stimulates flowering – but that is only a hypothesis and there is no concrete evidence pointing to this path.
The research also found that this type of behavior of bees is more frequent when there is a shortage of pollen in the environment, which leads hungry insects to stimulate the appearance of new flowers to feed in the future. One of the times when the strategy is most used is when bees wake up from hibernation earlier than expected – in these cases, there are fewer flowers available due to the time of year. In addition, two different species participated in the study and had similar results, suggesting that the behavior is not specific and appears to be generalized at least for the genus Bombus (the most common type of bee in Europe). Finally, the team repeated the experiment with bees raised outside the laboratory, to make sure it was not something specific to those specimens, and the result remained the same.
The researchers also believe that the strategy is a response to climate changes of anthropic cause, which deregulate the natural flowering cycles of plants due to the increase in temperature, causing flowering to happen during times when bees are hibernating, for example. "The demonstration that the damage caused by bees has strong effects on the time of flowering can have important ecological implications, including for the resilience of plant-pollinator interactions against anthropogenic environmental changes," wrote the authors in the study.