The controversy over glyphosate has so far focused only on its safety, for agricultural workers and consumers. A team of German researchers from the University of Konstanz and the Max-Planck Institute sheds light on the debate on its environmental effects.
In a study published Friday, June 3 in Sciencebiologist Anja Weidenmüller and her co-authors show for the first time that the famous herbicide – the most widely used synthetic pesticide in the world – alters the capacity of terrestrial bumblebee colonies (Bombus terrestris) to regulate the temperature of their nest. An effect that only occurs when these pollinators experience dietary stress and threatens their ability to reproduce.
In the laboratory, the researchers cut about fifteen colonies in half. In each of them, one half was exposed through food to low levels of glyphosate – comparable to those encountered in the environment –, the other half serving as a control. The researchers then simulated a stressful situation by reducing available food resources, a common situation in agricultural landscapes, especially when large-scale weeding destroys weed flora.
They then observed a drop in the ability of insects to keep their nest at a temperature above 28°C. However, the larvae of these insects only develop properly between 28°C and 35°C. “At 25°C alone, their survival rate drops by 17% and the development rate drops by more than 50% compared to the optimal rate”write the researchers.
Menaces d’extinction
According to the researchers’ measurements, exposure to glyphosate can thus reduce by 25% the incubation time during which the insects manage to maintain their nest in the narrow band of temperatures allowing their offspring to develop. “Our results show a large impact, especially when ambient temperatures are lowwrite the authors. This suggests that the effects of glyphosate on the colony may be particularly potent in early spring, when solitary queens raise their first brood on their own, and in the early phase of colony development, when colonies are still small. » Long-term exposure, they add, could thus have “significant consequences” on the reproductive success of insects.
These results are all the more important since about a quarter of European bumblebee species are threatened with extinction, and these insects form one of the most important groups of pollinators, as necessary for the reproduction of many species of wild flowers as to the maintenance and yields of certain food productions.
You have 41.83% of this article left to read. The following is for subscribers only.