Here, I relate what the journalist said in his article “Mais où sont passés tous les insectes ?”. All quotes, originally in French, were translated by me.
The decline of insects is manifested by the fact that the windshields of automobiles, even the less aerodynamic ones, are no longer soiled by the impacts of insects along the road. Science has “all the trouble in the world to quantify this discreet disappearance”, however a study published by Science focused on this subject.
In 1989, entomologists from the Krefeld Entomological Society (Hallman et al. 2017) set a series of traps in a wetland, Orbroich Bruch Nature Reserve (Germany) and quantified the amount of insects captured. The same device in 2013 captured an 80% lower mass of insects. The iteration of the operation in 2014 found similar results. The main suspects, according to this study, are the NNIs. Their use is said to be defended by agrochemists who market these products on the grounds that they are important to feed humanity.
However, the depletion of entomofauna is also a problem for farmers, as shown in a study published in late April by the journal Arthropod-Plant Interactions. Three researchers from the University of Helsinki observed that rape, an oilseed close to rapeseed, had seen its yields decrease since 1993. In Finland, it was harvested 1.7 tonnes per hectare compared to 1.2 today. It would be in the areas where the use of NNI would have been the most intense that the loss of yields would have been the greatest. On the contrary, crops insensitive to the depletion of insects, such as barley and wheat, didn’t suffer from these drops in productivity. (Hokkanen et al. 2013)
According to Vincent Bretagnolle and Bernard Vaissière, it’s just a correlation. However, the Finnish authors write “only the adoption of neonicotinoid insecticides in seed treatment can explain the drop in yields in several [Finnish] provinces, and at the national level for the shuttle, through a disruption of pollination services. by wild insects”.
The journalist concludes:
“Despite an increasingly indefensible case, the manufacturers of these substances are determined to defend them tooth and nail in front of the European regulator, to keep them forcefully on the market. An intense lobbying campaign is underway in Brussels and in the Strasbourg parliament – its outcome will be very interesting. “