Experimental evidence for neonicotinoid driven decline in aquatic emerging insects

Proceedings of the National Academy of Sciences, vol. 118

Abstract

There is an ongoing unprecedented loss in insects, both in terms of richness and biomass. The usage of pesticides, especially neonicotinoid insecticides, has been widely suggested to be a contributor to this decline. However, the risks of neonicotinoids to natural insect populations have remained largely unknown due to a lack of field-realistic experiments. Here, we used an outdoor experiment to determine effects of field-realistic concentrations of the commonly applied neonicotinoid thiacloprid on the emergence of naturally assembled aquatic insect populations. Following application, all major orders of emerging aquatic insects (Coleoptera, Diptera, Ephemeroptera, Odonata, and Trichoptera) declined strongly in both abundance and biomass. At the highest concentration (10 µg/L), emergence of most orders was nearly absent. Diversity of the most species-rich family, Chironomidae, decreased by 50% at more commonly observed concentrations (1 µg/L) and was generally reduced to a single species at the highest concentration. Our experimental findings thereby showcase a causal link of neonicotinoids and the ongoing insect decline. Given the urgency of the insect decline, our results highlight the need to reconsider the mass usage of neonicotinoids to preserve freshwater insects as well as the life and services depending on them.

Authors 6

1. S. Henrik Barmentlo corresponding Aachen Institute of Environmental Sciences (CML)

   Leiden University

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University, 2300 RA Leiden, The Netherlands;

2. Maarten J. J. Schrama Aachen Institute of Environmental Sciences (CML)

   Leiden University

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University, 2300 RA Leiden, The Netherlands;

3. G.R. de Snoo Aachen Institute of Environmental Sciences (CML)

   Leiden University · Netherlands Institute of Ecology

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University, 2300 RA Leiden, The Netherlands;

   Netherlands Institute of Ecology, 6700 AB Wageningen, The Netherlands;

4. Peter M. van Bodegom Aachen Institute of Environmental Sciences (CML)

   Leiden University

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University, 2300 RA Leiden, The Netherlands;

5. Andre van Nieuwenhuijzen
   Affiliation as printed

   Adviesbureau Haliplus, 378 46 Roseč, Czech Republic

6. Martina G. Vijver Aachen Institute of Environmental Sciences (CML)

   Leiden University

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University, 2300 RA Leiden, The Netherlands;