emamectin-benzoate and azamethiphos

Traditional bioassays are still necessary to test sensitivity of sea lice species to chemotherapeutants, but the methodology applied by the different scientists has varied over time in respect to that proposed in "Sea lice resistance to chemotherapeutants: A handbook in resistance management" (2006). These divergences motivated the organization of a workshop during the Sea Lice 2016 conference "Standardization of traditional bioassay process by sharing best practices." There was an agreement by the attendants to update the handbook. The objective of this article is to provide a baseline analysis of the methodology for traditional bioassays and to identify procedures that need to be addressed to standardize the protocol. The methodology was divided into the following steps: bioassay design; material and equipment; sea lice collection, transportation and laboratory reception; preparation of dilution; parasite exposure; response evaluation; data analysis; and reporting. Information from the presentations of the workshop, and also from other studies, allowed for the identification of procedures inside a given step that need to be standardized as they were reported to be performed differently by the different working groups. Bioassay design and response evaluation were the targeted steps where more procedures need to be analysed and agreed upon.

Topics: Animals; Antiparasitic Agents; Aquaculture; Biological Assay; Copepoda; Ectoparasitic Infestations; Fish Diseases; Hydrogen Peroxide; Ivermectin; Organothiophosphates; Pyrethrins; Reference Standards

Diflubenzuron and teflubenzuron are benzoylureas that are used in aquaculture to control sea lice. Flubenzurons have low toxicity to many marine species such as fish and algae but by their nature are likely to have significant adverse effects on nontarget species such as crustaceans and amphipods. Although the exact mechanism of toxicity is not known, these compounds are thought to inhibit the production of the enzyme chitin synthase during molting of immature stages of arthropods. These chitin synthesis inhibitors are effective against the larval and pre-adult life stages of sea lice. Due to their low solubility and results of recent monitoring studies conducted in Norway, the sediment compartment is considered the most likely reservoir for these compounds and possible remobilization from the sediment to benthic crustaceans could be of importance. For this reason, the epibenthic copepod Tisbe battagliai was selected for investigations into the acute and developmental effects of these compounds. For comparative purposes, azamethiphos was investigated to identify differences in sensitivity and act as a negative control for developmental effects at environmentally relevant concentrations. Standard acute studies with adult copepods showed little or no acute toxicity at milligrams per liter levels with the flubenzurons, whereas a naupliar developmental test demonstrated that environmentally relevant concentrations (e.g., nanograms per liter) caused a complete cessation of molting and finally death in the exposed copepods.

Topics: Animals; Aquaculture; Benzamides; Copepoda; Diflubenzuron; Disaccharides; Ivermectin; Life Cycle Stages; Organothiophosphates; Pesticides; Toxicity Tests, Acute; Veterinary Drugs; Water Pollutants, Chemical

Topics: Animals; Antiparasitic Agents; Biological Assay; Chromatography, High Pressure Liquid; Copepoda; Dose-Response Relationship, Drug; Ectoparasitic Infestations; Fish Diseases; Ivermectin; Nitriles; Organothiophosphates; Parasitic Sensitivity Tests; Pyrethrins; Salmonidae; Seawater; Tandem Mass Spectrometry; Time Factors