Larval exposure to the neonicotinoid imidacloprid impacts adult size in the farmland butterfly Pieris brassicae

PeerJ. 2018 May 18;6:e4772. doi: 10.7717/peerj.4772. eCollection 2018.

Abstract

Populations of farmland butterflies have been suffering from substantial population declines in recent decades. These declines have been correlated with neonicotinoid usage both in Europe and North America but experimental evidence linking these correlations is lacking. The potential for non-target butterflies to be exposed to trace levels of neonicotinoids is high, due to the widespread contamination of agricultural soils and wild plants in field margins. Here we provide experimental evidence that field realistic, sub-lethal exposure to the neonicotinoid imidacloprid negatively impacts the development of the common farmland butterfly Pieris brassicae. Cabbage plants were watered with either 0, 1, 10, 100 or 200 parts per billion imidacloprid, to represent field margin plants growing in contaminated agricultural soils and these were fed to P. brassicae larvae. The approximate digestibility (AD) of the cabbage as well as behavioural responses by the larvae to simulated predator attacks were measured but neither were affected by neonicotinoid treatment. However, the duration of pupation and the size of the adult butterflies were both significantly reduced in the exposed butterflies compared to the controls, suggesting that adult fitness is compromised through exposure to this neonicotinoid.

Keywords: Butterflies; Neonicotinoids; Non-target; Pesticides.

Associated data

  • figshare/10.6084/m9.figshare.5769360

Grant support

Penelope R. Whitehorn was funded by an Impact Research Fellowship held at the University of Stirling. This work was also supported by grants from the Triodos Foundation, Zeist (Netherlands) and the Gravin van Bylandt Stichting, The Hague, (Netherlands). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.