The role of semiochemicals in host location and non-host avoidance by salmon louse (Lepeophtheirus salmonis) copepodids

R. J. E. Bailey, M. A. Birkett, Anna Ingvarsdottir, Anne Jennifer Mordue, William Mordue, Bridget Anne O'Shea, J. A. Pickett, L. J. Wadhams

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The role and identity of host and non-host chemical cues (semiochemicals) in host location and non-host avoidance for copepodid larvae of sea lice, Lepeophtheirus salmonis, was investigated using Y-tube behavioural bioassays, solid-phase extraction (SPE), and coupled gas chromatography - mass spectrometry (GC-MS). Using artificial seawater conditioned with the preferred salmonid host, Salmo salar, L. salmonis displayed high activation and directional responses in Y-tube assays to salmon-conditioned water (SCW), to an extract of SCW prepared by SPE, and to a vacuum distillate of the SPE extract. Similar responses were observed to two chemicals identified from SCW by coupled GC-MS: isophorone and 6-methyl-5-hepten-2-one. Dose-response studies with isophorone showed that copepodid responses across the range tested were maximised at 0.01 and 0.1 mg center dot mL(-1). A mixture of isophorone and 6-methyl-5-hepten-2-one also induced high activation and directional responses. Semiochemicals were also isolated from the non-host fish, turbot (Scophthalmus maximus (Rafinesque)), by SPE and analysed by GC-MS. Two non-host-specific chemicals were identified as 2-aminoacetophenone and 4-methylquinazoline. When SCW was mixed with either of the non-host chemicals, activation and directional responses to SCW were eliminated in the Y tube.

Original languageEnglish
Pages (from-to)448-456
Number of pages8
JournalCanadian Journal of Fisheries and Aquatic Sciences
Publication statusPublished - 2006


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Bailey, R. J. E., Birkett, M. A., Ingvarsdottir, A., Mordue, A. J., Mordue, W., O'Shea, B. A., ... Wadhams, L. J. (2006). The role of semiochemicals in host location and non-host avoidance by salmon louse (Lepeophtheirus salmonis) copepodids. Canadian Journal of Fisheries and Aquatic Sciences, 63, 448-456.