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Common pesticides associated with extreme reduction of freshwater insects

Henrik Balmentoro and Professor Martina Viver working in the Living Lab. Credits: Edwin Giesbers

The widely used pesticide thiacloprid can cause a large-scale decline of freshwater insects. It was discovered by researchers in Leiden’s Living Lab. For three months, they counted insects flying in 36 grooves in the lab.Their research is PNAS..


In a ditch in the living lab, Henrik Balmentoro and his colleagues exposed freshwater insects to varying concentrations of thiacloprid. This substance belongs to the neonicotinoid, a group of the most widely used pesticides in the world. “We used realistic concentrations,” says Barmentlo. They correspond to the concentrations we actually measure in surface water.

Dramatic decline of all species

It has already been proven that neonicotinoids can be harmful to many insects. However, there was no conclusive evidence that these pesticides were at least partially responsible for the decline of scale insects.

Therefore, in a unique experiment, researchers caught more than 55,574 insects that jumped out of the lab’s 36 thiacloprid-contaminated ditches over a three-month period. After that, they identified all the specimens. They compared the results with nine control grooves without the addition of thiacloprid. Barmentoro: “We saw dramatic declines in all species groups surveyed, including dragonflies, beetles, and Cyperus microiria. In both absolute numbers and total biomass. In the most extreme scenarios, the most species-rich group. A variety of dance flies was seen, even falling into a single species. “

Impact on the entire ecosystem

And all these insects play an important role in the ecosystem. For example, they serve as food for bird species that eat many insects.Previously, other researchers have already said that these birds Race The more neonicotinoids in the water, the lower the number.Valmentoro: “So these are Bird seeds I’m suffering from a shortage of insects, in other words food. “

Barmentlo calls the result alarming. “Given the urgency of a large-scale reduction of insects, we think the heavy use of these pesticides should be reconsidered. In the EU, the use of thiacloprid was banned last year, but in the world Not yet banned elsewhere. To protect freshwater insects and all life dependent on them, we must stop using these neonicotinoids as soon as possible. ”


The effect of insecticides on damselflies is greater than expected


For more information:
S. Henrik Barmentlo et al, Experimental Evidence of Neonicotinoid Decay in Aquatic Appearance Insects, Minutes of the National Academy of Sciences (2021). DOI: 10.1073 / pnas.2105692118

Provided by
Leiden University

Quote: Common pesticides associated with extreme reduction of freshwater insects (October 26, 2021), https: //phys.org/news/2021-10-common-insecticide-linked-extreme-decline.html Obtained from October 26, 2021

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Common pesticides associated with extreme reduction of freshwater insects

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