RNAi pesticide authorized in the United States: soon in Europe ?

© JEAN-FRANCOIS MONIER/AFP/Archives

More discreetly than in the medical world, RNA has also been creeping into the agricultural landscape for several years now. So much so that the United States Environmental Protection Agency -United States (EPA) approved last April the use of Calantha, a new RNAi pesticide to fight the notorious Colorado potato beetle. The debates are launched: what effectiveness, what health risks, quid of biodiversity ? These are the questions and ideas that the westerly winds are likely to bring to Europe very soon.

It’s no secret that the global agricultural landscape is undergoing a transformation, with the emergence of new technologies aimed at increasing yields while reducing environmental impacts. On paper, at least. Among these innovations, RNAi pesticides have recently positioned themselves as an alternative to traditional chemicals and GMOs, the very name of which can raise a storm of protest.

Calantha, neither first nor last on the market

Unlike its predecessors, which work by poisoning harmful insects, these new substances use a more subtle approach: RNA interference (or RNA interference, RNA-i). This method involves introducing into the target organism a few RNA molecules designed to interfere with the expression of certain specific genes, thus causing the death or inability of the insect to reproduce. The idea behind all this, in theory, is to be able to specifically target the gene and/or species that is disturbing without affecting the rest, by relying on a mechanism that is relatively natural, since plants themselves react like this when they are in danger.

The terrain is slippery, so companies are keeping a low profile, but are investing no less. There are already tomatoes that don’t age, apples that don’t turn brown, and corn fields that defend themselves against worms by producing genes that can kill them, thanks to an RNAi insecticide created by Monsanto and authorized in 2017. Unsurprisingly, the American company, then recently bought by the German company Bayer, didn’t wait a second to establish itself in the market. Nor has it forgotten the good old lobbying methods. As reported by Usbek&Rica in 2018, while Bayer was making deals here and there with start-ups specializing in the manufacture of equipment or phytosanitary products, Monsanto was writing an 81-page letter to the EPA to avoid “regulation similar to that on GMOs”.

Seven years later, here comes Calantha, created by the company GreenLight Biosciences. The latter is intended to be sprayed on potato crops to eliminate the greatest destroyer: the Colorado potato beetle. In theory, the RNAi sequence thus spread would come into contact with the pest, act on the DNA sequences sent to the surface of its cells and modify its protein production so that it cannot survive. The problem is that we do not yet know what this spraying will trigger besides that.

We will see

While the promises associated with RNAi pesticides are enticing, particularly because they would avoid the use of harmful chemicals, the technology is not without its share of concerns. Critics point to the lack of scientific perspective on the long-term effects of these products, both on the environment and on human health.

One of the main points of controversy concerns the potential impact of RNA pesticides on non-target species. Indeed, although RNA molecules are designed to be specific to a given species, there is a risk that similar genetic sequences may be present in other organisms nearby, causing unwanted side effects. As explained by Usbek&Rica, since RNAi sequences are very short, “it is quite possible that they are common to several species. By targeting the Colorado potato beetle, we may unknowingly attack the ladybug”. It would therefore be necessary, as Olivier Lemaire, research director at INRA, suggests, “to sift through the genome of all off-target species”. And you can imagine that Bayer-Monsanto does not have time for that, any more than GreenLight Biosciences, which is buying their technology patents. Moreover, the EPA itself does not hesitate to obscure all this a little, only partially revealing the stages of the product evaluation process.

Some researchers therefore fear that this technology could have unpredictable ecological consequences, irreversibly disrupting natural balances. In addition, the idea that RNA molecules could be absorbed by plants and eventually end up in the human food chain raises health concerns. Although preliminary studies have not yet demonstrated clear risks to human health, critics of this technology are calling for more research before large-scale commercialization. This is reminiscent of the debates that took place around the mRNA anti-Covid vaccine, or the many health scandals that Monsanto drags around like ball and chain.

To defend itself, the company behind Calantha assures on its website that the pesticide “degrades rapidly in soil and water and does not harm bees, butterflies and other non-target insects or mammals”.

In any case, it is a safe bet that Europe will be the next battlefield for or against RNAi pesticides, with Bayer being closely connected to the United States, notably via Monsanto. To be continued, then.

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