When plants reproduce, the pollen is produced by the male organs, anthers, to fertilize the egg. This pollen is dust that can be moved to the female organ by wind, water or by animals. Since the upper Jurassic period, relationships between plants and insects have formed called mutualisms, where the insect will move the pollen from one plant to another of the same species, in exchange for nectar, produced by the flower.
Some of the most prominent, modern pollinating insects are bumblebees (Khalifa et al, 2021). In early spring, the queen bee emerges from hibernation ready to lay eggs. She needs a way of feeding her brood so she goes on flights to nearby flowers to collect nectar.
Climate change is leading to later flowering times for different plants that bees rely on for nectar, this is because the winters are generally much colder than previous years, meaning that it takes longer to reach a temperature that is suitable for the flowers in spring. While the plants are flowering later, the queen bees are still ready for spring at the same time, year after year; this is an issue since there is less nectar available for the bees to feed to their brood. Without plentiful food, there is a decline in the health of the offspring`, and a higher rate of bee death!
In response to the later flowering time, queen bees have been seen to bite holes in the leaves of flowering plants. This appears to speed up blooming, therefore releasing nectar for the bees to collect.
Are the queens really causing the flowers to bloom earlier?
To test whether the queens were actually increasing the speed of flowering, the researchers collected the queen bees (who had already mated) from the Swiss Alps; these were ready to lay eggs, whereas non- mated queens were raised in the lab. They were kept in enclosures with pre-flowered Brassica nigra (black mustard plants), this meant they were experiencing pollen depletion, as they would in nature.
The queens created holes in the leaves, seen in figure one, and they was tested alongside plants which had holes made in them by the scientists. Both groups of plants were timed to see how long it took for them to flower. This method was repeated with queens of many different bumblebee species, that are native to different areas. Figure two shows a diagram of how the experiment worked.
Figure one– shows the typical result of damage by the queen. (add link to source)
Figure two– a diagram to show the two different methods of damaging the plant leaves. The left shows a bee making holes in the leaves and the right shows scissors (representing manmade damage) making holes in the leaves.
What was the outcome of the experiments?
The scientists found that the plants that were bitten by the queens bloomed significantly quicker than those damaged using tools in the lab.
It is currently thought that damage caused by the queen bee speeds up the flowering process because their saliva contains chemicals that tell the plants to hurry up! While scientists are still trying to find out what exactly these chemicals are, it is likely they mimic compounds produced by the plant itself when it is ready to produce flowers.
What does this mean for the bees?
The results of this paper give an interesting insight into the way that bees are responding to climate change. When living things are faced with unusual and undesirable conditions, the main responses are for them to move to another location that is favourable, adapt to the new conditions or die, meaning there would be a local extinction of that species in the particular ecosystem (Corlett & Westcott, 2013). This behaviour is an example of an adaptation.
This behaviour can be reassuring when faced with a future of climate change, since bumblebees are some of the most economically important pollinators, accounting for one third of the food that humans consume (Khalifa et al, 2021).
Original Article: https://www.nature.com/articles/s41467-024-44785-3
References
Flury et al, 2025. “Leaf-damaging behaviour by queens is widespread among bumblebee species” Commun Biol 14;8:435 10.1038/s42003-025-07670-3
Corlett & Westcott, 2013. “Will plant movement keep up with climate change?” Trends in Ecology and Evolution. Vol 28, issue 8 482-488 https://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(13)00105-5?large_figure=true
Khalifa et al, 2021. “Overview of Bee pollination and its economic value for crop production.” Insects, 31;12(80) https://doi.org/10.3390/insects12080688
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