Broad-scale pesticide screening finds anticoagulant rodenticide and legacy pesticides in Australian frogs

Jodi J L Rowley; Andrew Symons; Christopher Doyle; Jane Hall; Karrie Rose; Laura Stapp; Damian C Lettoof

doi:10.1016/j.scitotenv.2024.172526

Broad-scale pesticide screening finds anticoagulant rodenticide and legacy pesticides in Australian frogs

Sci Total Environ. 2024 Jun 20:930:172526. doi: 10.1016/j.scitotenv.2024.172526. Epub 2024 Apr 16.

Authors

Jodi J L Rowley¹, Andrew Symons², Christopher Doyle², Jane Hall³, Karrie Rose³, Laura Stapp², Damian C Lettoof⁴

Affiliations

¹ Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, New South Wales 2010, Australia; Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences (BEES), University of New South Wales, Sydney, New South Wales 2052, Australia.
² New South Wales Department of Climate Change, Energy, the Environment and Water, Environment Protection Science Branch, 480 Weeroona Road, Lidcombe, New South Wales 2141, Australia.
³ Australian Registry of Wildlife Health, Taronga Conservation Society Australia, Bradley's Head Road, Mosman, NSW 2088, Australia.
⁴ Environment, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Centre for Environment and Life Sciences, Floreat, Western Australia 6014, Australia; School of Molecular and Life Sciences, Curtin University, Brand Drive, Bentley, Western Australia 6102, Australia.

PMID: 38636866
DOI: 10.1016/j.scitotenv.2024.172526

Abstract

Pesticide contamination poses a significant threat to non-target wildlife, including amphibians, many of which are already highly threatened. This study assessed the extent of pesticide exposure in dead frogs collected during a mass mortality event across eastern New South Wales, Australia between July 2021 and March 2022. Liver tissue from 77 individual frogs of six species were analysed for >600 legacy and contemporary pesticides, including rodenticides. More than a third (36 %) of the liver samples contained at least one of the following pesticides: brodifacoum, dieldrin, DDE, heptachlor/heptachlor epoxide, fipronil sulfone, and 2-methyl-4-chlorophenoxyacetic acid (MCPA). Brodifacoum, a second-generation anticoagulant rodenticide, was found in four of the six frog species analysed: the eastern banjo frog (Limnodynastes dumerilii), cane toad (Rhinella marina), green tree frog (Litoria caerulea) and Peron's tree frog (Litoria peronii). This is the first report of anticoagulant rodenticide detected in wild amphibians, raising concerns about potential impacts on frogs and extending the list of taxa shown to accumulate rodenticides. Dieldrin, a banned legacy pesticide, was also detected in two species: striped marsh frog (Limnodynastes peronii) and green tree frog (Litoria caerulea). The toxicological effects of these pesticides on frogs are difficult to infer due to limited comparable studies; however, due to the low frequency of detection the presence of these pesticides was not considered a major contributing factor to the mass mortality event. Additional research is needed to investigate the effects of pesticide exposure on amphibians, particularly regarding the impacts of second-generation anticoagulant rodenticides. There is also need for continued monitoring and improved conservation management strategies for the mitigation of the potential threat of pesticide exposure and accumulation in amphibian populations.

Keywords: Amphibians, bioindicator; Bioaccumulation; Ecotoxicology, mortality event.

MeSH terms

Animals
Anticoagulants* / analysis
Anura*
Australia
Environmental Monitoring*
New South Wales
Pesticides*
Rodenticides* / analysis

Substances

Rodenticides
Anticoagulants
Pesticides