| dc.description.abstract | The arthropod salmon louse (Lepeophtheirus salmonis) is a significant hazard to aquaculture and to the wild Atlantic salmon. In a monoculture environment, very high host densities may result in rapid reproduction and in the creation of pest waves. Pest control is critical for the health of farmed salmon and increased lice abundance is a potential threat for wild fish for a sustainable fish farming. Pesticides, physical treatments, construction modifications, fallowing, breeding, vaccination and biological control have all been used to manage and control salmon lice infestations. Most solutions are only partially effective, and up to now, no single method has fulfilled the required pest control needed. As with agriculture, lice/pest control is an arms race, and the marine environment complicates the task of precisely targeting the pest while avoiding unintentional harmful effects on the host. We have provided an overview of the techniques and ideas used to control salmon lice infestations and discuss present potential and constraints. Additionally, we discuss the possibilities for arthropod control in aquaculture using new techniques and supporting technologies like genome editing, RNA interference and machine learning.
Phenylalanine hydroxylase (PAH) is a crucial enzyme involved in tyrosine biosynthesis, having roles in neurological and physiological processes. The purpose of PAH has received little attention in crustaceans despite extensive investigations in other arthropods. We have characterised the PAH gene for the first time in the parasite Lepeophtheirus salmonis, a copepod responsible for substantial economic losses in salmonid fish farming. Phylogenetic and sequence analyses have confirmed that LsPAH is closely related to the metazoan PAH with conserved regulatory and catalytic domains. Temporal expression patterns revealed that LsPAH is expressed throughout all developmental stages, peaking during the copepodite stages, which suggests an essential role in developmental physiology. We used RNA interference (RNAi) to knock down LsPAH expression in the nauplius I stage to study developmental function during the larval stages. PAH knockdown has impaired larval development, moulting and swimming ability, exhibiting severe morphological defects.
Salmon lice have been a source of concern for the aquaculture sector, posing significant hazards to salmonid farming. Numerous treatment strategies have been explored to eradicate the parasite. Treatment efficacy must be maximised, and systematic genetic variations must be investigated across subpopulations to monitor and improve targeted control efforts against louse species. We employed IIb-RAD sequencing along with a random forest classification method to characterise the regional genetic structure of salmon lice in a north to south transect along the Norwegian coast and to uncover critical markers for sex differentiation in this species. We found 19428 single nucleotide polymorphisms (SNPs) from 95 salmon lice individuals. However, these SNPs could not separate the differential structure of lice populations. We picked 91 SNPs that are critical for regional classification and 14 SNPs essential for sex categorisation using the random forest approach. SNP data from spatially significant regions significantly increased genetic knowledge of population organisation and categorised regional demographic clusters throughout the Norwegian coast. Additionally, we identified SNP markers that may help determine the sex of the salmon louse. A substantial proportion of the SNPs under directional selection was also classified as highly significant by the random forest classification. Our data suggest that salmon lice showed a regional population pattern related to their geographical position along the Norwegian coast. | en_US |
