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
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.
KeywordsAmphibian Immunity Leukocytes Parasite Neonicotinoid Cercariae
We thank F. Maisonneuve and E. Pelletier from Environment and Climate Change Canada for their help and support with the chemical analyses.
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.
- Beaver PC (1937) Experimental studies on Echinostoma revolutum (Froelich), a fluke from birds and mammals. Ill Biol Monogr 15:1–96Google Scholar
- Fournier DA, Skaug HJ, Ancheta J, Ianelli J, Magnusson A, Maunder MN, Nielsen A, Sibert J (2012) AD Model Builder: using automatic differentiation for statistical inference of highly parameterized complex nonlinear models. Optim Methods Softw 27:233–249. https://doi.org/10.1080/10556788.2011.597854 CrossRefGoogle Scholar
- Fox J, Weisberg S (2011) Cox proportional-hazards regression for survival data in R. In: An R companion to applied regression, second edi. Sage, Thousand Oaks, pp 1–20Google Scholar
- Harris ML, Bishop CA, Struger J, Ripley B, Bogart JP (1998) The functional integrity of northern leopard frog (Rana pipiens) and green frog (Rana clamitans) populations in orchard wetlands. Effects of pesticides and eutrophic conditions on early life stage development. Environ Toxicol Chem 17:1351–1363. https://doi.org/10.1002/etc.5620170720 CrossRefGoogle Scholar
- Kuznetsova A, Brockhoff PB, Haubo Bojesen R (2016) lmerTest: tests in linear mixed effects models. R package version 2.0–33Google Scholar
- MacCulloch RD (2002) The ROM field guide to amphibians and reptiles of Ontario. McClelland & Stewart LtdGoogle Scholar
- OECD (2009) Test no. 231: amphibian metamorphosis assay, OECD guidelines for testing of chemicals section 2: effects on biotic systems. 33Google Scholar
- Orlofske SA, Belden LK, Hopkins WA (2013) Larval wood frog (Rana [= Lithobates] sylvatica) development and physiology following infection with the trematode parasite, Echinostoma trivolvis. Comp Biochem Physiol A Mol Integr Physiol 164:529–536. https://doi.org/10.1016/j.cbpa.2012.12.013
- Orlofske SA, Belden LK, Hopkins WA (2017) Effects of Echinostoma trivolvis metacercariae infection during development and metamorphosis of the wood frog (Lithobates sylvaticus). Comp Biochem Physiol A Mol Integr Physiol 203:40–48. https://doi.org/10.1016/j.cbpa.2016.08.002
- Paetow LJ, McLaughlin JD, Cue RI et al (2012) Effects of herbicides and the chytrid fungus Batrachochytrium dendrobatidis on the health of post-metamorphic northern leopard frogs (Lithobates pipiens). Ecotoxicol Environ Saf 80:372–380. https://doi.org/10.1016/j.ecoenv.2012.04.006 CrossRefGoogle Scholar
- Puglis HJ, Boone MD (2011) Effects of technical-grade active ingredient vs. commercial formulation of seven pesticides in the presence or absence of UV radiation on survival of green frog tadpoles. Arch Environ Contam Toxicol 60:145–155. https://doi.org/10.1007/s00244-010-9528-z CrossRefGoogle Scholar
- R Core Team (2017) R: a language and environment for statistical computing, 3.4.0. Doc. Free. available internet http//www. r-project. orgGoogle Scholar
- Robinson SA, Richardson SD, Dalton RL, Maisonneuve F, Trudeau VL, Pauli BD, Lee-Jenkins SSY (2017) Sublethal effects on wood frogs chronically exposed to environmentally relevant concentrations of two neonicotinoid insecticides. Environ Toxicol Chem 36:1101–1109. https://doi.org/10.1002/etc.3739 CrossRefGoogle Scholar
- Robinson SA, Richardson SD, Dalton RL, Maisonneuve F, Bartlett AJ, Solla SR, Trudeau V, Waltho N (2019) Assessment of sub-lethal effects of neonicotinoid insecticides on the life-history traits of two frog species. Environ Toxicol Chem. https://doi.org/10.1002/etc.4511
- Rohr JR, Civitello DJ, Crumrine PW, Halstead NT, Miller AD, Schotthoefer AM, Stenoien C, Johnson LB, Beasley VR (2015) Predator diversity, intraguild predation, and indirect effects drive parasite transmission. Proc Natl Acad Sci 112:3008–3013. https://doi.org/10.1073/pnas.1415971112 CrossRefGoogle Scholar
- Skaug HJ, Fournier DA, Bolker BM, et al (2016) Generalized linear mixed models using “AD Model Builder”Google Scholar
- Therneau T (2015) A package for survival analysis in S, version 2.38Google Scholar
- Trudeau VL, Schueler FW, Navarro-Martin L, Hamilton CK, Bulaeva E, Bennett A, Fletcher W, Taylor L (2013) Efficient induction of spawning of northern leopard frogs (Lithobates pipiens) during and outside the natural breeding season. Reprod Biol Endocrinol 11:14. https://doi.org/10.1186/1477-7827-11-14 CrossRefGoogle Scholar
- USEPA (2003) EFED risk assessment for the seed treatment of clothianidn 600FS on corn and canola. 91pp. Available online at: https://www3.epa.gov/pesticides/chemsearch/clearedreviews/csrPC-04430920-Feb-03_a.pdf Accessed 31 Jan 2019
- Zuur AF, Hilbe JM, Ieno EN (2015) A beginner’s guide to GLM and GLMM with R. Highland Statistics Ltd., NewburghGoogle Scholar