Bumblebees less likely to land on flowers sprayed with fertilizer – study

Bumblebees are less likely to land on flowers sprayed with fertilizer due to certain changes associated with the chemicals, experts have said.

Scientists at the University of Bristol have found that treating flowers with commonly used synthetic fertilizers causes the electric field around the flowers to change, making it more difficult for bees to identify the species.

The researchers said the findings, published in the journal PNAS Nexus, could have important consequences for pollination, with negative impacts on the natural world.

Dr Ellard Hunting, from the School of Biological Sciences at the University of Bristol, who is the lead author of the paper, said: “We know chemicals are toxic, but we know little about how they affect the immediate interaction between plants and pollinators.

Bees use clues like the smell and color of flowers, but they also use electric fields to identify plants

Bees use cues like the smell and color of flowers, but they also use electric fields to identify plants (Nubia Hunting/University of Bristol)

“Flowers have a range of signals that attract bees to promote feeding and pollination.

“For example, bees use cues like the smell and color of flowers, but they also use electric fields to identify plants.

“So a big problem is – agrochemical application can distort floral signals and alter the behavior of pollinators like bees.”

For the study, researchers investigated the effect of commercially available fertilizers in the UK on different types of floral signals used by bees.

When tested on lavenders, they observed that the sprays did not affect vision and smell, but there was a response in the electric field surrounding the flowers – lasting up to 25 minutes .

This change is noticeably longer than natural fluctuations, such as those caused by wind, experts said.

The scientists then simulated a rain event to see if the effects were reversed.

They observed that the plant had the same long-lasting response when it rained after using the sprays.

A similar effect was also seen when the researchers sprayed the lavenders with a pesticide called imidacloprid, which is banned for outdoor use in the UK and EU but still used in the US and around 100 other countries.

Dr Hunting said: ‘The fact that fertilizers affect the behavior of bees by altering the way they experience their physical environment gives new insight into how humans disturb the natural environment.

“Imagine not being able to tell the apples from the tomatoes because someone sprayed chemicals in the vegetable aisle.

“This may be relevant to all organisms that use the electric fields that are virtually everywhere in the environment.”

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