Neonicotinoids thiamethoxam and clothianidin adversely affect the colonisation of invertebrate populations in aquatic microcosms
Environmental Science and Pollution Research
Neonicotinoids thiamethoxam and clothianidin adversely affect the colonisation of invertebrate populations in aquatic microcosms
Kate Basley 0
Dave Goulson 0
Kate Basley 0
Dave Goulson 0
0 School of Life Sciences, The University of Sussex , Falmer, East Sussex BN1 9QG , UK
Surface waters are sometimes contaminated with neonicotinoids: a widespread, persistent, systemic class of insecticide with leaching potential. Previous ecotoxicological investigations of this chemical class in aquatic ecosystems have largely focused on the impacts of the neonicotinoid imidacloprid; few empirical, manipulative studies have investigated the effect on invertebrate abundances of two other neonicotinoids which are now more widely used: clothianidin and thiamethoxam. In this study, we employ a simple microcosm semi-field design, incorporating a one-off contamination event, to investigate the effect of these pesticides at field-realistic levels (ranging from 0 to 15 ppb) on invertebrate colonisation and survival in small ephemeral ponds. In line with previous research on neonicotinoid impacts on aquatic invertebrates, significant negative effects of both neonicotinoids were found. There were clear differences between the two chemicals, with thiamethoxam generally producing stronger negative effects than clothianidin. Populations of Chironomids (Diptera) and Ostracoda were negatively affected by both chemicals, while Culicidae appeared to be unaffected by clothianidin at the doses used. Our data demonstrate that field-realistic concentrations of neonicotinoids are likely to reduce populations of invertebrates found in ephemeral ponds, which may have knock on effects up the food chain. We highlight the importance of developing pesticide monitoring schemes for European surface waters. Responsible editor: Philippe Garrigues
Aquatic invertebrates; Neonicotinoids; Pesticides; Freshwater contamination
Introduction
The majority of species in freshwater aquatic ecosystems are
arthropods. These are an essential link in the transfer of energy
up the freshwater food chain, being a primary food source for
many species of vertebrates, such as fish, amphibians and
birds
(Chagnon et al. 2015)
. A decrease in arthropod
abundance or diversity is therefore likely to result in a loss of
important ecosystem processes and knock-on effects for
higher trophic levels
(Covich et al. 2004; Hallmann et al.
2014)
.
Small-scale aquatic habitats such as temporary ponds and
puddles often fulfil an important ecological role at the
landscape level
(De Meester et al. 2005)
. Similarly, ditches are
crucial features for land drainage and, if managed properly,
can also provide habitats for wildlife. Although such
ephemeral habitats are the least species rich of the freshwater features
in an agricultural landscape, they have been found to support a
diversity of specialist temporary water invertebrates
(Williams
2004)
.
Nicolet et al. (2004)
, found that, of 71 temporary ponds
surveyed in England and Wales, 75% of these supported at
least one nationally scarce macro-invertebrate and 8%
supported at least one nationally scarce plant species across a
range of physico-chemical characteristics.
Globally, neonicotinoids have become the most widely
used insecticides due in part to their systemic properties in
the crop to be protected and also their relatively
lowvertebrate toxicity
(Jeschke et al. 2011)
. However, with the
exception of the Netherlands, most countries in Europe and
other parts of the world do not have a system in place for the
systematic monitoring of neonicotinoid pesticides in aquatic
systems, although the monitoring of pesticide presence in
water is required under the European Drinking Water Directive
(Allan et al. 2006)
. It has been shown that at the global scale,
more than 50% of detected insecticide concentrations exceed
regulatory levels, indicating that surface waters and therefore
aquatic biodiversity are at risk of harm from current
insecticide use
(Stehle and Schulz 2015)
. In the UK, a 2-m protection
zone must be left around ditches and watercourses in all fields
of 2 ha or more to minimise water contamination
(DEFRA
2006)
. However, the risk of contamination via neonicotinoid
seed dressings is not currently addressed; the only stipulation
in their use is that treated seeds are kept away from surface
water, which does not account for the possibility of lateral
movement of neonicotinoids through the soil profile nor
movement of the pesticide in surface runoff.
There are widespread concerns as to their potentially
farreaching impacts upon wildlife
(Chagnon et al. 2015; Goulson
2013; Hallmann et al. 2014; Pisa et al. 2015; Van Dijk et al.
2013; Whitehorn et al. 2012)
. Neonicotinoids and their toxic
metabolites have been found to be persistent, not just in the
target plant, but also in water, aquatic sediments and soil
(van
der Sluijs et al. 2013)
. A recent review conclu (...truncated)