A quarter of European bumblebees species, one group of most important pollinators, is threatened with extinction.
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The controversy over glyphosate has so far been brought to its health security, for agricultural workers and consumers. A team of German researchers from the University of Constance and the Max-Planck Institute sheds light on its environmental effects.
In a study published Friday, June 3 in Science, the biologist Anja Weidenmüller and her co -authors show for the first time that the famous herbicide – the most used synthetic pesticides in the world – alters the capacity of the colonies of terrestrial bumblebees ( Bombus land) to regulate the temperature of their nest. An effect that only occurs when these pollinators undergo food stress and which threatens their reproductive capacity.
In the laboratory, the researchers cut in two about fifteen colonies. In each of them, half was exposed by food at low levels of glyphosate – comparable to those encountered in the environment – the other half serving as a witness. The researchers then simulated a stressful situation by reducing available food resources, frequent situation in agricultural landscapes, especially when large -scale weeding destroys the Adventice flora.
They then found a sagging of the capacity of insects to keep their nest at a temperature above 28 ° C. However, the larvae of these insects only develop between 28 ° C and 35 ° C. “If only at 25 ° C, their survival rate drops by 17 % and the development rate drops by more than 50 % compared to the optimal rate,” write researchers.
threats extinction
According to researchers’ measures, exposure to glyphosate can thus drop the time of incubation by 25 % during which insects manage to maintain their nest in the narrow strip of temperatures allowing their offspring to develop . “Our results show a significant impact, especially when the ambient temperatures are low, write the authors. This suggests that the effects of glyphosate on the colony can be particularly powerful in early spring, when the solitary queens raise their first briefs alone, and In the early phase of the development of the colony, when the colonies are still small. “Long-term exposure, they add, could thus have” important consequences “on the reproductive success of insects.
These results are all the more important than about a quarter of European bumblebees are threatened with extinction, and that these insects form a group of among the most important pollinators, as much necessary for the reproduction of many species of Wild flowers than to the maintenance and yields of certain food productions.
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