A review of host finding behaviour in the parasitic sea louse, Lepeophtheirus salmonis (Caligidae: Copepoda)

Abstract

Ectoparasitic sea lice are the most important parasite problem to date for the salmon farming industry in the northern and southern hemispheres. An understanding of host location in the specialist species, Lepeophtheirus salmonis, the most important louse species in the North Atlantic, is now being realized using behavioural in vitro and in vivo bioassays coupled with chemical analysis of fish conditioned waters. Both physical and chemical cues are important in host location. Responses of sea lice to physical cues such as light and salinity may enable them to gather in areas where host fish are likely to be found. Mechanoreception is an important sensory modality in host location and acts by switching on specific behaviours that enable landing on a fish. Chemoreception plays a defining role in host location and recognition. The detection of host kairomones switches on 'host search' behavioural patterns and also induces landing responses whereas non-host kairomones fail to induce attraction or significant landing behaviour. Semiochemicals derived from salmon and also non-host fish have been identified, and may prove useful for the development of integrated pest management strategies, by the introduction of odour traps for monitoring lice numbers, and by the use of stimulo-deterrent diversionary (push:pull) strategies in their control.

Identification of non-host semiochemicals for the brown dog tick, Rhipicephalus sanguineus sensu lato (Acari: Ixodidae), from tick-resistant beagles, Canis lupus familiaris

“…To the best of our knowledge, this is the first study demonstrating the presence of natural repellents mediating the behaviour of ticks in resistant animals. These results are similar to those observed in other interactions that have demonstrated the presence of natural repellents in certain hosts, such as in the waterbuck K. defassa in relation to Glossina morsitans (Diptera: Glossinidae) (Gikonyo et al, 2000;Saini et al, 2013); cattle in relation to Haematobia irritans (Diptera: Muscidae) Jensen et al, 2004); salmon in relation to Lepeophtheirus salmonis (Caligidae: Copepoda) (Bailey et al, 2006;Mordue and Birkett, 2009) Repellency was deemed to exist if the number of ticks on the untreated side of the Petri dish was higher than the number on the control side, according to the chi-square test. * Significant (p < 0.05).…”

A common-garden experiment to quantify evolutionary processes in copepods: the case of emamectin benzoate resistance in the parasitic sea louse Lepeophtheirus salmonis

“…[24] and has developed strategies required for survival, proliferation and host location in low densities across long distances [25]. The life cycle of L. salmonis comprises eight stages, each separated by moults [21,26,27].…”

Disease management mitigates risk of pathogen transmission from maricultured salmonids

“…The extent of dispersion during early larval development is largely determined by currents in the ambient seawater (Tully & Nolan 2002). Host-seeking and attachment by the copepodid is facilitated by anatomical, physiological and behavioural traits (see Mordue & Birkett 2009). In the absence of treatment, high host densities combined with appropriate environmental conditions support rapid growth in the size of the parasite population with associated scale loss, skin ulceration and haemorrhage (Brandal & Egidius 1977, Wootten et al 1982, Johnson et al 2004).…”