Natural plant defences put to use

Natural plant defences put to use

Plants release scents to repel pests. Research shows that these natural signals could also be used as herbicides. The approach is exciting, but it is not a panacea – conventional pesticides remain indispensable.

Tuesday, January 21, 2025

Plants are not mute beings – they communicate with each other via chemical signals and use them to repel pests. The NZZ newspaper recently reported on this sophisticated pest control method. When plants sense danger, they release scents to protect themselves from predators. At the same time, they warn neighbouring plants and attract beneficial insects. Studies such as those conducted by Matthias Erb at the University of Bern show that these scents could play a key role in plant protection – for example, in the form of gentle insecticides.

Erb's team simulated the infestation of maize plants by carving small holes in the leaves of the plants and adding moth saliva. The plants reacted immediately: they released scents that killed the supposed predators while attracting parasitoid wasps, the natural enemies of the pests.


More than 1,500 different molecules identified worldwide

Similar mechanisms have already been discovered in other plants. For example, thale cress – a popular research model plant – reacts to chemical signals in the air within seconds. The amount of calcium ions increases immediately. Scientists from Japan have captured the phenomenon on video using a special calcium imaging technique.

However, plants do not only release small, volatile molecules into the air when they sense danger, but continuously. ‘A plant's physiological state is reflected in its bouquet of scents,’ Erb is quoted in the NZZ article. Over 1,500 different volatile organic molecules have already been identified worldwide, providing information about the identity and condition of plants. Nevertheless, research is still in its infancy. It is still unclear whether these mechanisms apply to all plants.


Industry develops new solutions

However, not only science, but also companies such as Bayer and Syngenta are already taking advantage of these findings and conducting research in this area. Bayer has launched ‘FLiPPER’, a biological insecticide based on natural fatty acids that selectively targets pests without endangering beneficial insects. Syngenta, in turn, drew inspiration from a natural phenomenon: One of their scientists observed that no weeds grew under the myrtle plant Callistemon citrinus. It turned out that the plant excretes the fragrance leptospermone. This eventually served as a template for the herbicide mesotrione developed by Syngenta, which was first marketed under the product name Callisto.


No mysticism, but no cure-all either

Erb strictly avoids formulations such as ‘communication between plants’: ‘So far, there is no serious evidence that plants send out chemical signals specifically to communicate with other plants.’ The idea of talking trees and shrubs that warn each other of danger and help each other may sound nice, says Erb, but it is ‘esoteric nonsense’. It should also be noted that although these natural approaches are promising, it would be naive to believe that they can solve the challenges of crop protection. Natural pesticides serve as a supplement, but not as a substitute for conventional pesticides. These remain indispensable for a resource-efficient agriculture – just as synthetically or biotechnologically produced drugs for humans and animals.

Kindly note:

We, a non-native editorial team value clear and faultless communication. At times we have to prioritize speed over perfection, utilizing tools, that are still learning.

We are deepL sorry for any observed stylistic or spelling errors.

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