Effects of chronic exposure to clothianidin on the earthworm Lumbricus terrestris

Basley, Kate and Goulson, Dave (2017) Effects of chronic exposure to clothianidin on the earthworm Lumbricus terrestris. PeerJ, 5. e3177. ISSN 2167-8359

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Abstract

Although neonicotinoids are targeted at insects, their predominant use as a seed
dressing and their long persistence in soils mean that non-target soil organisms such as
earthworms are likely to be chronically exposed to them. Chronic exposure may pose
risks that are not evaluated in most toxicity tests. We experimentally tested the effect
of field-realistic concentrations of a commonly used neonicotinoid, clothianidin, on
mortality, weight gain, and food consumption to assess the impacts of chronic exposure
over four months on fitness of L. terrestris individuals. We undertook three separate
experiments, each with different exposure routes: treated soil only (experiment A),
treated food and soil combined (experiment B) and treated food only (experiment
C). Mortality was negatively affected by exposure from treated soil only with greatest
mortality observed in the groups exposed to the two highest concentrations (20 ppb
and 100 ppb), but no clear effect on mortality was found in the other two experiments.
When clothianidin was present in the food, an anti-feedant effect was present in months
one and two which subsequently disappeared; if this occurs in the field, it could result in
reduced rates of decomposition of treated crop foliage. We found no significant effects
of any treatment on worm body mass. We cannot rule out stronger adverse effects if
worms come into close proximity to treated seeds, or if other aspects of fitness were
examined. Overall, our data suggest that field-realistic exposure to clothianidin has a
significant but temporary effect on food consumption and can have weak but significant
impacts on mortality of L. terrestris.

Item Type: Article
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Subjects: Q Science
Depositing User: David Goulson
Date Deposited: 02 Nov 2017 15:34
Last Modified: 07 Nov 2017 15:17
URI: http://sro.sussex.ac.uk/id/eprint/70880

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