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Sub-chronic exposure to a neonicotinoid does not affect susceptibility of larval leopard frogs to infection by trematode parasites, via either depressed cercarial performance or host immunity

  • Stacey A. RobinsonEmail author
  • M. J. Gavel
  • S. D. Richardson
  • R. J. Chlebak
  • D. Milotic
  • J. Koprivnikar
  • M. R. Forbes
Immunology and Host-Parasite Interactions - Original Paper

Abstract

Little information is available on the effects of neonicotinoid insecticides on vertebrates. Previous work using amphibians found chronic exposure to some neonicotinoids had no detrimental effects on fitness-relevant traits. However, there is some evidence of more subtle effects of neonicotinoids on immune traits and evidence that other pesticides can suppress tadpole immunity resulting in elevated levels of parasitism in the exposed tadpoles. The objective of our study was to assess whether neonicotinoid exposure affected tadpole immunometrics and susceptibility to parasitic helminths. We assessed northern leopard frog tadpole (Lithobates pipiens) levels of parasitism and leukocyte profiles following exposure to environmentally relevant concentrations of clothianidin and free-living infective cercariae of a helminth parasite, an Echinostoma sp. trematode. When comparing tadpoles from controls to either 1 or 100 μg/L clothianidin treatments, we found similar measures of parasitism (i.e. prevalence, abundance and intensity of echinostome cysts) and similar leukocyte profiles. We also confirmed that clothianidin was not lethal for cercariae; however, slight reductions in swimming activity were detected at the lowest exposure concentration of 0.23 μg/L. Our results show that exposure to clothianidin during the larval amphibian stage does not affect leukocyte profiles or susceptibility to parasitism by larval trematodes in northern leopard frogs although other aspects such as length of host exposure require further study.

Keywords

Amphibian Immunity Leukocytes Parasite Neonicotinoid Cercariae 

Notes

Acknowledgements

We thank F. Maisonneuve and E. Pelletier from Environment and Climate Change Canada for their help and support with the chemical analyses.

Funding information

Funding for this project was provided by Environment and Climate Change Canada (SR01-2016).

Compliance with ethical standards

Conflict of interest

The authors declare that there is no conflict of interest.

Statement on the welfare of animals

All applicable international, national and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted (Environment and Climate Change Canada Wildlife Eastern Animal Care Committee, SR01-2016). This article does not contain any studies with human participants performed by any of the authors.

Supplementary material

436_2019_6385_MOESM1_ESM.docx (27 kb)
ESM 1 (DOCX 27 kb)
436_2019_6385_MOESM2_ESM.xlsx (38 kb)
ESM 2 (XLSX 37 kb)

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© Crown 2019

Authors and Affiliations

  1. 1.National Wildlife Research Centre, Wildlife and Landscape Science Directorate, Environment and Climate Change CanadaOttawaCanada
  2. 2.Department of BiologyCarleton UniversityOttawaCanada
  3. 3.Department of Chemistry and BiologyRyerson UniversityTorontoCanada

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