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Sea lice exposure to non-lethal levels of emamectin benzoate after treatments: a potential risk factor for drug resistance

Lam, C T; Rosanowski, S M; Walker, M; St-Hilaire, S

Authors

C T Lam

S M Rosanowski

M Walker

S St-Hilaire



Abstract

The avermectin derivative emamectin benzoate (EMB) has been widely used by salmon industries around the world to control sea lice infestations. Resistance to this anti-parasitic drug is also commonly reported in these industries. The objective of this study was to quantify the number of sea lice potentially exposed to sub-lethal concentrations of EMB while fish clear the drug after treatments. We assessed juvenile sea lice abundance after 38 EMB treatments on six Atlantic salmon farms, in a small archipelago in British Colombia, Canada, between 2007 and 2018. We fitted a standard EMB pharmacokinetic curve to determine the time when fish treated with this product would have EMB tissue concentrations below the recommended target therapeutic level. During the study, we estimated that for each sea lice treatment there was, on average, an abundance of 0.12 juvenile sea lice per fish during the time period when the concentrations of EMB would have been lower than 60ppb, the recommended therapeutic treatment level for sea lice. The findings from this study on metaphylactic anti-parasitic treatments identify a potential driver for drug resistance in sea lice that should be further explored.

Citation

Lam, C. T., Rosanowski, S. M., Walker, M., & St-Hilaire, S. (2020). Sea lice exposure to non-lethal levels of emamectin benzoate after treatments: a potential risk factor for drug resistance. https://doi.org/10.1038/s41598-020-57594-7

Journal Article Type Article
Acceptance Date Jan 3, 2020
Publication Date Jan 22, 2020
Deposit Date Jan 10, 2020
Publicly Available Date Mar 29, 2024
Journal Scientific Reports (Nature)
Peer Reviewed Peer Reviewed
Volume 10
Issue 932
DOI https://doi.org/10.1038/s41598-020-57594-7
Public URL https://rvc-repository.worktribe.com/output/1378887

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