A multivariable assessment of the spatio-temporal distribution of pyrethroids performance on the sea lice Caligus rogercresseyi in Chile

Spat Spatiotemporal Epidemiol. 2018 Aug:26:1-13. doi: 10.1016/j.sste.2018.04.004. Epub 2018 May 8.

Abstract

Synthetic pyrethroids have been widely used in Chile to control the sea lice Caligus rogercresseyi, a major ectoparasite of farmed salmon. Although resistance of C. rogercresseyi to pyrethroids has been reported in Chile, there is no information regarding the geographic extent of this problem. In this study we explored the spatial and temporal variation of C. rogercresseyi's response to pyrethroids in Chile from 2012 to 2013. We modeled lice abundance one week after treatment with a linear mixed-effects regression, and then we performed spatial and spatio-temporal cluster analyses on farm-level effects and on treatment-level residuals, respectively. Results indicate there were two areas where the post-treatment lice counts were significantly higher than in the rest of the study area. These spatial clusters remained even once we adjusted for environmental and management predictors, suggesting unmeasured factors (e.g. resistance) were causing the clustering. Further investigation should be carried out to confirm this hypothesis.

Keywords: Caligus; Multivariable analysis; Pyrethroids; Spatio-temporal analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antiparasitic Agents / administration & dosage
  • Antiparasitic Agents / pharmacology*
  • Aquaculture
  • Chile / epidemiology
  • Copepoda / drug effects*
  • Drug Resistance
  • Ectoparasitic Infestations / epidemiology
  • Ectoparasitic Infestations / prevention & control
  • Ectoparasitic Infestations / veterinary*
  • Female
  • Fish Diseases / epidemiology*
  • Fish Diseases / parasitology
  • Fish Diseases / prevention & control
  • Linear Models
  • Male
  • Pyrethrins / administration & dosage
  • Pyrethrins / pharmacology*
  • Salmo salar / parasitology*
  • Spatio-Temporal Analysis

Substances

  • Antiparasitic Agents
  • Pyrethrins