Not a single fly leaves here without invitation. Between the two doors of Entomopolis, sticky traps and an ultraviolet lamp intercept any insect in freedom. Precaution is required in this pavilion of the Sophia Agrobiotech Institute in Antibes (Provence-Alpes-Cote d'Azur), because there are invasive insects that are ravaging France and other exotic species that are being considered to introduce in the countryside to fight the first. We organize biological control.
"Currently, crop protection relies heavily on synthetic chemicals. The methods of biocontrol allow a defense much more respectful of the environment and human health, " says Thibaut Malausa, scientific coordinator of biocontrol at the National Institute of Agricultural Research (INRA), to which the Sophia Agrobiotech Institute is attached . Biocontrol involves pitting insects, bacteria, viruses or fungi against harmful organisms, dispersing odorous molecules away from them, spreading natural substances to kill them, or rearranging the landscape to favor the presence of their natural enemies. .
"Biological control has existed since the end of XIX th century, but it is undeveloped because chemical pesticides were very affordable. Today, we are back, "said Christian Lannou, head of plant health and environment at INRA. The efforts of the Mediterranean research center are mainly focused on protection against harmful insects. This is timely, since insecticides neonicotinoid family will be banned in France on 1 st September and that farmers urgently need alternatives to these neurotoxic decimating honeybees. However, in a notice published on May 30, the Health Security Agency (ANSES) noted that the methods of biocontrol appear"Best able to replace neonicotinoids immediately, effectively and sustainably".
For the moment, the use of biocontrol is rare in French cultures. Despite rapid growth (10% to 15% per year), this approach represents only 5% of the insecticide market, and its use is concentrated in the greenhouse.
Tiny wasps, big impact
Forty species of insects - good and bad - are studied at Entomopolis, where the engineer Nicolas Borowiec hands us a small vial which, at first glance, seems empty. "Look well: there are hundreds in there, maybe thousands of insects," hesays. Despite their small size, the micro-wasps of the trichogramma family found there are powerful enemies of pests. As "oophagous parasitoids", they deposit their larvae inside eggs laid by other insects. After a few days, the parasitized eggs turn black and the host embryo feeds the young trichograms. Even before its birth, the pest is eliminated.
The first trichogramma services in France date back to the 1980s, when insects were released to control corn borer. It was the INRA researchers in Antibes who, for ten years, had conducted the trials before the marketing of the treatment. The trichogram protects today 150 000 hectares of maize in France each year. It must be released in large numbers at the time of spawning - this is called biological flood control.
However, when entomologists release a species knowing that it will be implanted durably in the territory, it is "biological control by acclimation". This is the second option that researchers are putting to fight the codling moth, the aggressor that motivates 30% to 40% of insecticide treatments in orchards in France.
In 2015, Nicolas Borowiec and his colleagues traveled to New Zealand to collect 500 micro-wasps Mastrus ridens . This indigenous parasitoid from Kazakhstan, a natural enemy of codling moth, has been successfully established in the New Zealand archipelago and in several other countries of the world. However, before releasing him to Europe, the team had to make sure that the insect would not attack non-target species. After years of study at Entomopolis, researchers are now ready to release the first Mastrus ridens as soon as they get the funding. "The probability of success is very high", according to Nicolas Borowiec.
In the nearby containment room, another miniature wasp occupies the researchers. It is opposed to Drosophila suzukii , a fly of Japanese origin that spoils many fruits, including cherries, berries and apricots. Producers are helpless in the face of this attacker who arrived in Europe in 2008, especially since the 2016 ban on the most effective insecticide to kill him (dimethoate) for public health reasons. However, the micro-wasp Ganaspis , another oophagous parasitoid, likes to deposit its larvae in the eggs of Drosophila suzukii . If all goes well, the first releases could take place in 2019. However, nothing is guaranteed: Ganaspis has never been introduced in a new environment.
Fight the mushroom with the mushroom
Obviously, biological control with insects requires farmers to adapt their practices. They must watch very carefully the arrival of pests and, at the first sign, have biodegradable insect diffusers in their culture. Because of these complications, manufacturers prefer to offer biocontrol products based on bacteria, fungi or toxins, which they can sell in bottles. Moreover, it is the bacterium Bacillus thuringiensis ( Bt ) which currently composes 70% of sales of bioinsecticides worldwide. Very popular in organic farming, Bt particularly targets butterfly larvae.
INRA researchers are working to identify new micro-organisms to fight other pests. In a room of the Sophia Agrobiotech Institute, the researcher Michel Ponchet shows his latest findings, the Y3 and Pseudozyma fungi . In Petri dishes, we see the two fungi that completely neutralize downy mildew, gray rots and white rot. These fungal diseases attack a very wide spectrum of plants (including vines, tomatoes, rapeseed). "The mushrooms we found will now have to be adapted industrially by a company," explains Michel Ponchet.It will have to decide whether it sells them as spores, if it extracts toxins or if it reproduces toxins synthetically. "
Indeed, the commercial development of products is not the lot of INRA. After identifying the most promising methods, the institute gives the relay to the private sector, which integrates them into salable products. "Here, we do the fundamental work that will be applied in ten years," summarizes Christian Lannou. Nature hides a multitude of alternatives to synthetic chemical pesticides, but you have to take the time to discover them.
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