Contamination of the Aquatic Environment with Neonicotinoids and its Implication for Ecosystems

Abstract

The widespread use of systemic neonicotinoid insecticides in agriculture results first in contamination of the soil of the treated crops, and secondly in the transfer of residues to the aquatic environment. The high toxicity of these insecticides to aquatic insects and other arthropods has been recognized, but there is little awareness of the impacts these chemicals have on aquatic environments and the ecosystem at large. Recent monitoring studies in several countries, however, have revealed a worldwide contamination of creeks, rivers and lakes with these insecticides, with residue levels in the low µg/L (ppb) range. The current extent of aquatic contamination by neonicotinoids is reviewed first, and the findings contrasted with the known acute and chronic toxicity of neonicotinoids to various aquatic organisms. Impacts on populations and aquatic communities, mostly using mesocosms, are reviewed next to identify the communities most at risk from those that undergo little or no impact. Finally, the ecological links between aquatic and terrestrial organisms are considered. The consequences for terrestrial vertebrate species that depend mainly on this food source are discussed together with impacts on ecosystem function. Gaps in knowledge stem from difficulties in obtaining long-term experimental data that relates the effects on individual organisms to impacts on populations and ecosystems. The paper concludes with a summary of findings and the implications they have for the larger ecosystem.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

“…Regarding neonicotinoids, the most recent review of surveys in 11 countries found the frequency of detections between 13% (acetamiprid) and 57% (dinotefuran) of their surface waters and current residue levels ranging from an average 80 ng/L (dinotefuran) to 730 μg/L (imidacloprid). Both frequency and residue levels showed increasing trends over the past 10 years, in agreement with their increasing use as pest control products all over the word (Sánchez-Bayo et al 2016a).…”

Pesticides from the EU First and Second Watch Lists in the Water Environment

“…Risks to other organisms have also been identified . More recent in vitro, in vivo, and ecological field studies indicate that neonicotinoids can have adverse effects on vertebrate and invertebrate species, as well as mammals .…”

“…[22,46] Risks to other organisms have also been identified. [47][48][49] More recent in vitro, in vivo, and ecological field studies indicate that neonicotinoids can have adverse effects on vertebrate and invertebrate species, as well as mammals. [50] In addition, certain neonicotinoid metabolites have been found to be as or more toxic than the parent compound.…”

Postregistration monitoring of pesticides is urgently required to protect ecosystems

“…If not available in the risk assessment, exposure in connected off-site ecosystems can be considered based on generic assumptions, for example, we consider an agricultural field of 250 m  250 m with a ditch on 2 sides having the standard 30 cm depth  2 m width and 250 m length (details given in Supplemental Data II). Most of the applied (80-97%) neonicotinoids from coated seeds end up in the soil and porewater (Goulson et al [16] and Sanchez-Bayo [14]), and leach into the groundwater and adjacent drainage ditches. In the most positive scenario, which uses a relatively fast degradation time (half-life ¼ 27 d) and 10 d of leaching before reaching the adjacent ditch system, concentrations in the ditches are approximately 38.7 mg/L.…”