Environment: Natural predators, alternative to pesticides

The return to the classic methods of doing certain things is also catching on in terms of environmental protection. Natural predators such as birds, beetles and spiders are an effective alternative to using pesticides in fields, reducing pest populations and increasing crop yields, a study reports. Dramatic decline in biodiversity, water and soil pollution, health risks: the massive use of chemical pesticides in agriculture has well-established negative consequences.

The authors of the new research, which was published in the journal "Proceedings of the Royal Society B", analyzed existing studies examining the alternative effectiveness of a form of "biocontrol", based on predators naturally present in fields. "Predators reduced pest populations by an average of 73% and increased crop yields by an average of 25%," concluded the authors of this meta-analysis. "Our study highlights that predators indirectly favor better agricultural yields and provide vital ecosystem services, which could persist even in the current context of climate change," explained researchers from Brazil, the United States and the Czech Republic. However, they did not directly compare the effectiveness of predators with that of synthetic pesticides, which was not evaluated in the study. But "many other articles demonstrate the damage that pesticides cause to ecosystems and biocontrol," notes Gabriel Boldorini, PhD student at the Brazilian University of Pernambuco and lead author of the study. "The message that must be remembered is that natural predators are good pest control agents and that their maintenance is essential to guarantee this control in the future, in the context of climate change," he emphasized. The researchers found that the efficiency generated by the presence of natural predators was greater in regions with greater variability in rainfall throughout the year-a feature that could increase in some regions with climate change, they note. Another conclusion: biocontrol by multiple predator species is no more effective than biocontrol by a single species. "In general, the more species there are, the better the ecosystems work. But there are also exceptions," revealed Gabriel Boldorini. As far as biocontrol is concerned, the presence of several predator species certainly allows targeting a greater diversity of pest types and which are in different stages of development. But on the other hand, predators can compete with each other or even eat each other.