Chemical sprays can scramble bees radars, new study finds

Pollinators can detect a change in the electrical field around flowers after they have been sprayed with chemical fertilisers or pesticides, which may consequently cause them to avoid the affected plants, scientists have discovered.

Close-up of insect on yellow flower

Noting that most studies on the impact of agrochemicals on pollinators focus on toxicity, Dr Ellard Hunting of Bristol’s School of Biological Sciences and his team carried out a study into how biophysical floral cues, which entice bees to feed and pollinate plants, can be influenced by chemical sprays.

The study, published in PNAS Nexus last week, found that pesticides and fertilisers do not necessarily alter the flower’s smell or appearance; however they can alter the electric field around flowers for up to 25 minutes after exposure. This impact lasts substantially longer than natural fluctuations, such as those caused by wind, and reduces bumblebee foraging and consequently pollination.

READ MORE: A green and poisoned land? The UK’s pesticide chokehold

The team mimicked the electrical changes caused by synthetic fertilisers and the neonicotinoid pesticide imidacloprid in the field by electrically manipulating flowers and discovered that bumblebees are able to detect and discriminate against small and dynamic electric field alterations.

Co-author of the study, published in PNAS Nexus, Sam England, said: “What makes this study important is that it’s the first known example of anthropogenic ‘noise’ interfering with a terrestrial animal’s electrical sense.”

Dr Ellard Hunting added: “The fact that fertilisers 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.”

The researchers said this study has opened the door to more questions, such as how other airborne particles such as nanoparticles, exhaust gases, nano-plastics, and viral particles may impact organisms that use these electrical fields as cues.