This text is the continuation of the article “#2 Reconciling sustainable agriculture and agro-ecology: reducing yield losses by maintaining a diversity of weeds?“.
Citizens (and political decision-makers) expect a lot from agro-ecology, to promote a new agriculture using fewer inputs. In fact, numerous research studies suggest that ecosystem services, rendered by the biodiversity of agricultural areas, would make it possible to greatly reduce the use of fertilizers or pesticides. However, this research is difficult to transpose into farmers’ practices.
In a new Agriculture & Environment article, we analyze an emblematic case: the biocontrol of rapeseed meligèthes. Despite more than 10 years of particularly innovative ecological research, this work has not led to the identification of agricultural practices that would make it possible to regulate this insect pest of rapeseed without insecticides, by promoting the action of its natural parasites. Worse, they have not even succeeded in demonstrating that the parasitic Hymenoptera studied are really capable of controlling meligether populations, something that conventional entomology studies would have made it possible to verify much more quickly. And the researchers’ recommendations appear to be quite contradictory with the advice of sustainable agriculture… Like the previous articles in the same series, this example illustrates the difficulty of demonstrating the existence of ecosystem services that can really be exploited by farmers if observational ecology studies are not complemented by conventional field experiments.