This article is taken from the monthly journal Sciences et Avenir – La Recherche #903 of May 2022.
A fight breaks out near Versailles (Yvelines). On the mezzanine floor of the Sensory Ecology Department on the National Research Institute for Agriculture, Food and the Environment (Inrae) campus in Grignon, researchers are developing solutions to combat the most dangerous insect pests in agriculture. Their model is the cotton moth (Spodoptera littoralis), a moth that feeds on tomatoes, potatoes or corn, between Africa and Europe. Present in Spain, Italy and Greece, it has yet to arrive in France. But it is she who grows the laboratory of the Institute of Ecology and Environmental Sciences in Paris. Target? Understand how his sense of smell works to deceive him. A track that would protect crops without destroying all life around. Because until now, heavy chemical weapons have been used in agriculture, responsible for the extinction of a quarter of insect populations in the last thirty years.
At first glance, the “nose” of insects is very different from the nose of mammals. Director of Sensory Ecology Emmanuel Jaquin-Joly shows the thin antennae of Spodoptera littoralis: “Its antennae are covered with small bristles, sensilla, which are 50 to 100 micrometers (µm) long and 1 to 5 µm in diameter, ten times smaller than a human hair. A lot of pores on their surface with a diameter of 0.1 to 0.2 microns are the entry point for odorous molecules. , or external, like antennae, the translation of smell into behavior (attraction, repulsion) follows a path common to all terrestrial species. Each olfactory receptor is actually connected to a neuron that will carry an electrical message to the brain. “In insects, the receptor is coupled to the co-receptor, and together they will produce an electrical signal,” the researcher continues. On the other hand, in mammals, the receptor is coupled to a protein that activates a cascade of reactions leading to an electrical signal, proving that the two systems have radically different evolutionary origins.” And because of this difference, the disturbance of the sense of smell of a moth or a beetle will not affect other families in the living world.