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What if the solution to devastating pest attacks wasn’t to kill the insects, but to convince them to go elsewhere? This is exactly what a team of scientists in Argentina is doing by making plant defend themselves.
Instead of using chemicals to attack pests, the scientists target the invisible conversation happening between plants and insects. In a warming world, the technology can benefit many countries, especially tropical ones like India, where pest attacks have not only intensified, but new pest species are destroying crops.
Plants emit odours and insects are guided by these invisible scent trails to find suitable plants to feed on or lay eggs in. What the scientists in Argentina have found is that by manipulating these odours that act as chemical signals sent by a plant, they can modify the behaviour of the pest; essentially confusing it and making the plant unattractive as a host.
At the forefront of this is Victoria Coll, a plant biologist and a researcher of plant insect interactions and the chemistry mediating those interactions.
“Smell is a universal language. Everyone uses it except for us humans (to interact),” she says. The method involves spraying plants with signalling compounds that will trigger genes that cause the plants to emit specific odours. These odours, from resistant plants that respond best to pest attacks, can induce a defence response in a particular crop, informs Coll.
“Modern hybrids have lost the ability to respond against pests,” she says, adding that they looked for landraces, some of them actually sown by indigenous communities and have better defence mechanisms, to make the compound.
Further, after applying the spray, some of the scents released by the treated plants attract parasitoid insects, natural enemies of crop pests. These beneficial insects don’t harm the plant, but they target and kill the pests.
For over a decade, Coll had been researching on the corn plant and its interaction with leafhopper, a yellow bug that has plagued corn fields from the US to Argentina and caused severe losses to its farmers.
In 2023, she, along with Emilio Molina, an Ecuadorian third-generation farmer, Alejandro Forlin an agronomical engineer, and entomologist Jorge Hill founded a start-up called Semion, which was born out of the shared frustrations with the limitations of traditional pest control methods.
Semion was among the six projects shortlisted for the $2 billion Food Planet Prize in Sweden that was announced in June 2025.
Semion is currently working on corn and citrus. To test their method, the team conducted extensive trials in fields and laboratories in the 2023 corn season in two countries — Paraguay and Argentina.
“We had 16 field experiments distributed along a large latitudinal gradient from Paraguay to Córdoba in Argentina,” says Coll. The goal was not just to see whether their formula could repel pests, but also whether it could mitigate the larger impact of pest-borne diseases on yields.
The results, Coll says, were promising. In treated corn plants that had already been infected, the team recorded a 30 per cent increase in yield compared to infected plants that were left untreated. “That’s a lot,” she says.
“We were able to reduce the colonisation levels of the pest, increase parasitism of the pest by natural enemies, and increase natural enemy recruitment in treated plants.” In other words, the method worked on multiple levels — disrupting pest behaviour while simultaneously strengthening the plant’s ability to attract helpful insects.
The team also ran controlled laboratory experiments to test the treatment under different conditions. These included both treated and untreated plants in infected and uninfected scenarios, helping them observe other possible benefits of the treatment beyond pest deterrence.
The treatment, however, is not a one-size-fits-all solution. “It depends on the species,” says Coll. “There’s no dose or specific blend that works in every plant.” Each formulation is tailored to a specific crop and pest. The process begins by studying the pest’s behaviour, what it is attracted to, what repels it, and then creating a formula that induces the right defensive response in the plant. “We make the plant reach this hormonal state where it produces the blend that we’re targeting,” she explains.
The formula is applied externally, using sprays containing natural volatile compounds, the same kinds of chemicals plants release on their own when under attack. In the case of corn, Semion applies the treatment five times during the crop’s vegetative stage, when plants are young and most vulnerable. “But we’re working on reducing that number. We think we can bring it down to two or three by improving the formulation.”
When asked if the compounds used in the blend are safe, Coll replied that these are not synthetic pesticides. They are plant-derived and biodegradable and regarded as safe.
“The good thing about these compounds is that they have been tested extensively in humans and other organisms because most of these compounds are actually part of scents, of blends of scents and perfume ingredients. So, we don’t expect them to harm non-target species, people, or the environment.
While Semion’s current focus is on corn and citrus, the team believes the technology can be adapted to a wide range of crops and regions.
In the near future, Coll is particularly interested in applying the method to soybean, a crop heavily impacted by stink bugs in Argentina and across South America.
The team is also working to ensure that the final product is priced competitively with chemical insecticides, making it accessible to farmers while offering a safer and more sustainable option.