Research: Fertilisers affect how bees see flowers

A new paper in PNAS Nexus, published by Oxford University Press, indicates that chemicals used in agriculture, like fertilizers and pesticides, can change the way bees ‘see’ a flower, and that this reduces the number of bees visiting a flower.

November 9, 2022


5 min


Oxford [UK], November 9 (ANI): According to a recent Oxford University Press study in PNAS Nexus, agricultural chemicals like fertilisers and pesticides can alter how bees perceive a flower, which in turn decreases the number of bees that visit a flower.
For the purpose of encouraging insect eating and pollination, flowers offer a wide variety of cues and attractants. Bees can navigate the environment by using colour, the sun, and magnetic fields. They recognise plants on a smaller scale by using cues like blossom colour and odour, as well as humidity and electric fields. Large-scale spray treatments are a common practice among farmers when it comes to applying chemical combinations, particularly fertilisers, to plants.
A significant source of pollution that has been related to declines in the quantity and variety of bee populations is the extensive use of chemicals in horticulture and agriculture.
Although many of these compounds have long been known to be hazardous, little is known about how agrochemicals disrupt the direct relationship between plants and pollinators. Flowers’ characteristics can change in a variety of ways when sprayed. Many chemicals used in agriculture have an electric charge that is intended to stick to plants. Therefore, spray applications may alter the electric fields that surround a flower. Thus, a key concern is whether the use of agrochemicals can skew floral cues and alter the behaviour of pollinators like bees.
Researchers here tested the effect of fertilizer sprays on various floral cues used by bees. They observed that the chemical did not affect vision and smell, but that there was a response in the electric field surrounding the flower. To visualize this, the researchers sprayed cut flowers with positively charged, coloured particles released as an aerosol.
The bio-electric potential in the stem of the flower was measured by the researchers to have a better understanding of what altered the bloom. The electromagnetic field that surrounds flowers has a significant source of this potential. The bio-electric potential was shown to be altered by chemical sprays for up to 25 minutes.
This change corresponds with reported reductions in bee-feeding attempts in nature, which last for around 20 minutes, and is significantly longer than natural fluctuations, such as those brought on by the wind. It’s interesting to note that scientists found the plant responded the same way after using chemicals and a simulated rain event, showing the effect lasts longer than the duration of the chemical use.
The researchers recreated the electrical alterations brought on by fertilisers in the field by electronically manipulating flowers in order to investigate if bees are indeed aware of the changes in the plant’s electrical signature.
They noticed that when bumblebees were flying toward the flowers, they were less eager to settle on an electrically altered flower than they were on an unaltered control flower. This demonstrated that bumblebees are able to recognise and distinguish between the modest, dynamic electric field changes brought on by agricultural pesticides.
The fact that fertilizers affect pollinator behaviour by interfering with the way an organism perceives its physical environment offers a new perspective on how human-made chemicals disturb the natural environment and emphasizes the importance of considering the seemingly hidden senses that are used by insects to understand and learn about their environment.
“That fertilizers affect bee behaviour by changing the way it experiences its physical environment gives a new perspective on how humans disturb the natural environment, said the paper’s lead author,” Ellard Hunting. “Imagine yourself not being able to distinguish apples from tomatoes because someone sprayed some chemicals in the vegetable department. This may be relevant for all organisms that use the electric fields that are virtually everywhere in the environment.” (ANI)

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