A new study questions the effectiveness of one of the most used pesticides in the European Union, lambda-cyhalothrin. This insecticide is used in cereal, tuber, and fruit crops in various countries and could be threatening up to 98% of beneficial insect species in these fields, according to research led by the Jagiellonian University in Poland, with the participation of the Barcelona Museum of Natural Sciences and the University of Barcelona (UB) through the Biodiversity Research Institute, as reported by Efe.
It is a pyrethroid insecticide (toxic to insects and mammals) with fast action, commonly used to control agricultural pests such as aphids, beetles, moths, mosquitoes, flies, and ticks that affect human health.
The results, published in the journal Science of The Total Environment, show that even when applied at the recommended dose, this product affects "very negatively" all insects it comes into contact with, leading researchers to question the safety of this pesticide.
Recent estimates indicate that insect diversity is decreasing at an alarming rate of 2.5% annually, resulting in the loss of approximately 25,000 species every 12 months.
In addition to climate change, habitat loss, and other causes, many of which are unknown, experts agree that one of the main drivers of this decline is the widespread use of synthetic pesticides in agriculture.
This is because these products not only eliminate crop-damaging species but also have a devastating impact on other insects, including those beneficial for key plant processes such as pollination, natural pest control, and nutrient cycling.
"Does not distinguish between pests and beneficial insects"
"Lambda-cyhalothrin does not distinguish between pests and beneficial insects for crops and poses a threat to biodiversity," explained Berta Caballero, arthropod curator at the Barcelona Museum of Natural Sciences and co-author of the article.
Thus, the pesticide used to eliminate a specific aphid or fly would also be killing ladybugs or spiders, which are their natural predators.
To conduct the analyses, researchers collected individuals from over 50 different insect species in representative crop fields from various climatic zones in five countries: Portugal, the United Kingdom, Germany, Poland, and Spain.
This extensive sampling allowed for evaluating the effects of this chemical on animals present in various agricultural ecosystems under different environmental conditions.
Insects captured in crops such as rapeseed, wheat, or olive trees were subsequently exposed to increasing doses of the pesticide, with monitoring over 72 hours.
"With just 5% of the recommended dose, half of the beneficial insect species are affected," warned José Manuel Blanco, a researcher specializing in agroecology at the UB Biodiversity Research Institute and co-author of the study. The expert affirmed that when the full dose is applied, this figure "rises to 98%."
This research also casts doubt on the reliability of studies used to approve new pesticides, as they often rely solely on tests with a single species: the honeybee, which is not representative due to its genetic and biological particularities.
"The results of this study point to an urgent need to redesign risk assessment procedures, incorporating multi-species approaches to protect biodiversity more effectively," concluded Dr. Blanco.