Don’t be fooled by its name: lambda-cyhalothrin (λ-cyhalothrin) is anything but a “lambda” pesticide. This insecticide from the pyrethroid family is in fact one of the most used in the European Union, particularly on crops of cereals, tubers (potatoes, for example) and fruits. And this is not without consequences on the ecosystem, according to a recent study.
Presenting their results in the journal Science of The Total Environment on September 23, 2024, European researchers captured insects in agricultural fields (rapeseed, wheat, olive trees, etc.) in five EU countries: Portugal, the United Kingdom , Germany, Poland and Spain. These specimens belonged to around fifty species beneficial to crops, known in particular to naturally regulate pest populations.
The collected insects were then exposed in the laboratory to increasing doses of λ-cyhalothrin, with monitoring for 72 hours. “With just 5% of the recommended dose, half of beneficial insect species are affected, a figure that increases to 98% when the full dose is applied”summarizes José Manuel Blanco-Moreno, researcher in agroecology at the Biodiversity Research Institute of the University of Barcelona, first author of the study, in a press release.
A pesticide that kills without distinction
Thus, the study reveals that when applied at the recommended dose, this pesticide has a strong negative effect on almost all insects with which it comes into contact.
“λ-cyhalothrin does not discriminate between harmful insects (such as aphids, certain beetles and moths, Editor’s note) and insects beneficial to crops (ladybugs and spiders)and constitutes a threat to the biodiversity“summarizes Berta Caballero, curator of arthropods at the Museum of Natural Sciences in Barcelona, co-author.
According to the most recent estimates, insect diversity is declining at an alarming rate of 2.5% per year (Ziesche et al., 2023), resulting in the loss of approximately 25,000 species each year, or nearly three per hour. In addition to climate change and habitat loss, the massive use of synthetic pesticides in agriculture is singled out as one of the main causes of this decline.
It’s not just the honey bee
The authors of this new study also question the reliability of studies used to approve new pesticides, since they are often based on tests carried out on a single species: the honey bee. However, despite its importance as a pollinator for obtaining various fruits, this insect is not representative of all biodiversity, they note.
“The results of this study show that there is an urgent need to review risk assessment procedures by integrating multi-species approaches in order to protect biodiversity more effectively”therefore concludes Dr Blanco-Moreno.
It appears “robustly” that plant protection products are, in agricultural areas, one of the main causes of the decline of terrestrial invertebrates, including pollinating insects and predators of pests (ladybugs, ground beetles, etc.), as well as birds, the National Research Institute has already highlighted for agriculture, food and the environment (INRAE) in 2022.
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