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

Bailey, R., Birkett, M., Ingvarsdóttir, A., Mordue, A. J., Mordue, W., O'Shea, B., Pickett, J. ORCID: https://orcid.org/0000-0002-8386-3770 and Wadhams, L. 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 (2) , pp. 448-456. 10.1139/f05-231

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Abstract

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·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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Chemistry
Publisher:	Canadian Science Publishing
ISSN:	0706-652X
Last Modified:	25 Feb 2026 12:30
URI:	https://orca.cardiff.ac.uk/id/eprint/185269

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