1
|
Trombetta E, Jakubiak S, Kutkova S, Lipschutz D, O’Hare A, Enright JA. A modeling study of the impact of treatment policies on the evolution of resistance in sea lice on salmon farms. PLoS One 2023; 18:e0294708. [PMID: 38019751 PMCID: PMC10686416 DOI: 10.1371/journal.pone.0294708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 11/08/2023] [Indexed: 12/01/2023] Open
Abstract
Salmonid aquaculture is an important source of nutritious food with more than 2 million tonnes of fish produced each year (Food and Agriculture Organisation of the United Nations, 2019). In most salmon producing countries, sea lice represent a major barrier to the sustainability of salmonid aquaculture. This issue is exacerbated by widespread resistance to chemical treatments on both sides of the Atlantic. Regulation for sea lice management mostly involves reporting lice counts and treatment thresholds, which depending on interpretation may encourage preemptive treatments. We have developed a stochastic simulation model of sea lice infestation including the lice life-cycle, genetic resistance to treatment, a wildlife reservoir, salmon growth and stocking practices in the context of infestation, and coordination of treatment between farms. Farms report infestation levels to a central organisation, and may then cooperate or not when coordinated treatment is triggered. Treatment practice then impacts the level of resistance in the surrounding sea lice population. Our simulation finds that treatment drives selection for resistance and coordination between managers is key. We also find that position in the hydrologically-derived network of farms can impact individual farm infestation levels and the topology of this network can impact overall infestation and resistance. We show how coordination and triggering of treatment alongside varying hydrological topology of farm connections affects the evolution of lice resistance, and thus optimise salmon quality within socio-economic and environmental constraints. Network topology drives infestation levels in cages, treatments, and hence treatment-driven resistance. Thus farmer behaviour may be highly dependent on hydrologically position and local level of infestation.
Collapse
Affiliation(s)
- Enrico Trombetta
- School of Computing Science, University of Glasgow, Glasgow, United Kingdom
| | - Sara Jakubiak
- School of Computing Science, University of Glasgow, Glasgow, United Kingdom
| | - Sara Kutkova
- School of Computing Science, University of Glasgow, Glasgow, United Kingdom
| | - Debby Lipschutz
- Usher Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Anthony O’Hare
- Computing Science and Mathematics, University of Stirling, Stirling, United Kingdom
| | - Jessica A. Enright
- School of Computing Science, University of Glasgow, Glasgow, United Kingdom
| |
Collapse
|
2
|
Yu T, Xu X, Mao H, Han X, Liu Y, Zhang H, Lai J, Gu J, Xia M, Hu C, Li D. Fenpropathrin exposure induces neurotoxicity in zebrafish embryos. FISH PHYSIOLOGY AND BIOCHEMISTRY 2022; 48:1539-1554. [PMID: 36266516 DOI: 10.1007/s10695-022-01134-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Fenpropathrin has been a commonly used insecticide to control agricultural and household insects over a few decades. Up to now, fenpropathrin residue in soil and water has been often determined due to its widespread use, which poses serious threat to environment and aquatic organisms. The potential of fenpropathrin to affect aquatic lives is still poorly understood. In this study, we used zebrafish (Danio rerio) embryo as an experimental model system to evaluate the toxicity of fenpropathrin to the development of zebrafish nervous system. Zebrafish embryos were separately exposed to fenpropathrin at the dose of 0.016 mg/L, 0.032 mg/L, 0.064 mg/L, starting at 6 h post-fertilizationhpf (hpf) up to 96 hpf. The results showed that fenpropathrin exposure gives rise to physiological, behavioral, and neurodevelopmental impairments in zebrafish embryos, including enhanced acetylcholinesterase (AChE) activity, abnormal swimming behavior, karyopyknosis in brain cells, increased intercellular space, and uneven migration of neuron in brain area. In addition, the expressions of genes concerning neurodevelopment and neurotransmitter system were inhibited following fenpropathrin exposure. We also found that fenpropathrin exposure distinctly induced oxidative stress by increasing reactive oxygen species (ROS) generation and inhibiting the production of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). Expectedly, some apoptosis-associated genes were induced and the apoptosis appeared in the brain and heart cells of zebrafish embryos. Moreover, fenpropathrin exposure also inhibited the expressions of genes in Nrf2 signaling pathway, such as heme oxygenase-1 (HO-1) and SOD. In summary, the results of this study indicate that oxidative stress-triggered apoptosis may be an underlying fundamental of fenpropathrin-induced neurotoxicity in zebrafish embryos.
Collapse
Affiliation(s)
- Tingting Yu
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Xiaowen Xu
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Huiling Mao
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Xue Han
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Yulong Liu
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Hongying Zhang
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Jingli Lai
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Jianfeng Gu
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Mengling Xia
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Chengyu Hu
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China
| | - Dongming Li
- School of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, China.
- School of Basic Medical Sciences, Fuzhou Medical College, Nanchang University, Fuzhou, 344000, Jiangxi, China.
| |
Collapse
|
3
|
Gaffney LP, Lavery JM. Research Before Policy: Identifying Gaps in Salmonid Welfare Research That Require Further Study to Inform Evidence-Based Aquaculture Guidelines in Canada. Front Vet Sci 2022; 8:768558. [PMID: 35155641 PMCID: PMC8835349 DOI: 10.3389/fvets.2021.768558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/24/2021] [Indexed: 11/30/2022] Open
Abstract
Aquaculture is a growing industry worldwide and Canadian finfish culture is dominated by marine salmonid farming. In part due to increasing public and stakeholder concerns around fish welfare protection, the first-ever Canadian Code of Practice for the Care and Handling of Farmed Salmonids was recently completed, following the National Farm Animal Care Council's (NFACC) rigorous Code development process. During this process, both the Scientific (responsible for reviewing existing literature and producing a peer-reviewed report that informs the Code) and Code Development (a diverse group of stakeholders including aquaculture producers, fish transporters, aquaculture veterinarians, animal welfare advocates, food retailers, government, and researchers) Committees identified research gaps in tandem, as they worked through the literature on salmonid physiology, health, husbandry, and welfare. When those lists are combined with the results of a public "top-of-mind" survey conducted by NFACC, they reveal several overlapping areas of scientific, stakeholder, and public concern where scientific evidence is currently lacking: (1) biodensity; (2) health monitoring and management, with a focus on sea lice infection prevention and management; (3) feed quality and management, particularly whether feed restriction or deprivation has consequences for welfare; (4) enclosure design, especially focused on environmental enrichment provision and lighting design; and (5) slaughter and euthanasia. For each of these five research areas, we provide a brief overview of current research on the topic and outline the specific research gaps present. The final section of this review identifies future research avenues that will help address these research gaps, including using existing paradigms developed by terrestrial animal welfare researchers, developing novel methods for assessing fish welfare, and the validation of new salmonid welfare indices. We conclude that there is no dearth of relevant research to be done in the realm of farmed salmonid welfare that can support crucial evidence-based fish welfare policy development.
Collapse
Affiliation(s)
- Leigh P. Gaffney
- National Animal Welfare Representative, Code Development Committee (NFACC) for the Code of Practice for the Care and Handling of Farm Animal Care Council (NFACC), Ottawa, ON, Canada
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - J. Michelle Lavery
- Scientific Committee (NFACC) for the Code of Practice for the Care and Handling of Farmed Salmonids, National Farm Animal Care Council (NFACC), Ottawa, ON, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| |
Collapse
|
4
|
Zhou Z, Eichner C, Nilsen F, Jonassen I, Dondrup M. A novel approach to co-expression network analysis identifies modules and genes relevant for moulting and development in the Atlantic salmon louse (Lepeophtheirus salmonis). BMC Genomics 2021; 22:832. [PMID: 34789144 PMCID: PMC8600823 DOI: 10.1186/s12864-021-08054-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/04/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The salmon louse (Lepeophtheirus salmonis) is an obligate ectoparasitic copepod living on Atlantic salmon and other salmonids in the marine environment. Salmon lice cause a number of environmental problems and lead to large economical losses in aquaculture every year. In order to develop novel parasite control strategies, a better understanding of the mechanisms of moulting and development of the salmon louse at the transcriptional level is required. METHODS Three weighted gene co-expression networks were constructed based on the pairwise correlations of salmon louse gene expression profiles at different life stages. Network-based approaches and gene annotation information were applied to identify genes that might be important for the moulting and development of the salmon louse. RNA interference was performed for validation. Regulatory impact factors were calculated for all the transcription factor genes by examining the changes in co-expression patterns between transcription factor genes and deferentially expressed genes in middle stages and moulting stages. RESULTS Eight gene modules were predicted as important, and 10 genes from six of the eight modules have been found to show observable phenotypes in RNA interference experiments. We knocked down five hub genes from three modules and observed phenotypic consequences in all experiments. In the infection trial, no copepodids with a RAB1A-like gene knocked down were found on fish, while control samples developed to chalimus-1 larvae. Also, a FOXO-like transcription factor obtained highest scores in the regulatory impact factor calculation. CONCLUSIONS We propose a gene co-expression network-based approach to identify genes playing an important role in the moulting and development of salmon louse. The RNA interference experiments confirm the effectiveness of our approach and demonstrated the indispensable role of a RAB1A-like gene in the development of the salmon louse. We propose that our approach could be generalized to identify important genes associated with a phenotype of interest in other organisms.
Collapse
Affiliation(s)
- Zhaoran Zhou
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008 Norway
| | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008 Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008 Norway
| | - Inge Jonassen
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008 Norway
| | - Michael Dondrup
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008 Norway
| |
Collapse
|
5
|
Sviland Walde C, Bang Jensen B, Pettersen JM, Stormoen M. Estimating cage-level mortality distributions following different delousing treatments of Atlantic salmon (salmo salar) in Norway. JOURNAL OF FISH DISEASES 2021; 44:899-912. [PMID: 33606885 DOI: 10.1111/jfd.13348] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
This retrospective descriptive study estimates cage-level mortality distributions after six immediate delousing methods: thermal, mechanical, hydrogen peroxide, medicinal, freshwater and combination of medicinal treatments. We investigated mortality patterns associated with 4 644 delousing treatment of 1 837 cohorts of farmed Atlantic salmon (Salmo salar) stocked in sea along the Norwegian coast between 2014 and 2017. The mortality is expressed as mortality rates. We found distributions of delta mortality rate within 1, 7 and 14 days after all six delousing treatments, using mortality rate within 7 days before treatments as baseline. The results show that we can expect increased mortality rates after all six delousing methods. The median delta mortality rates after thermal and mechanical delousing are 5.4 and 6.3 times higher than medicinal treatment, respectively, for the 2017 year-class. There is a reduction in the delta median mortality for thermal and freshwater delousing from 2015 to 2019. There is a wide variability in the mortality rates, in particular for thermal delousing. Our results suggest that the variability in delta mortality for thermal delousing has been reduced from the 2014 to 2017 year-class, indicating an improvement of the technique. However, a significant increase in the number of thermal treatments from 14 in 2015 to 738 in 2018 probably contributes to the overall increased mortality in Norwegian salmon farming.
Collapse
Affiliation(s)
| | | | | | - Marit Stormoen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| |
Collapse
|
6
|
Fjørtoft HB, Nilsen F, Besnier F, Stene A, Tveten AK, Bjørn PA, Aspehaug VT, Glover KA. Losing the 'arms race': multiresistant salmon lice are dispersed throughout the North Atlantic Ocean. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210265. [PMID: 34084551 PMCID: PMC8150044 DOI: 10.1098/rsos.210265] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Nothing lasts forever, including the effect of chemicals aimed to control pests in food production. As old pesticides have been compromised by emerging resistance, new ones have been introduced and turned the odds back in our favour. With time, however, some pests have developed multi-pesticide resistance, challenging our ability to control them. In salmonid aquaculture, the ectoparasitic salmon louse has developed resistance to most of the available delousing compounds. The discovery of genetic markers associated with resistance to organophosphates and pyrethroids made it possible for us to investigate simultaneous resistance to both compounds in approximately 2000 samples of salmon lice from throughout the North Atlantic in the years 2000-2016. We observed widespread and increasing multiresistance on the European side of the Atlantic, particularly in areas with intensive aquaculture. Multiresistant lice were also found on wild Atlantic salmon and sea trout, and also on farmed salmonid hosts in areas where delousing chemicals have not been used. In areas with intensive aquaculture, there are almost no lice left that are sensitive to both compounds. These results demonstrate the speed to which this parasite can develop widespread multiresistance, illustrating why the aquaculture industry has repeatedly lost the arms race with this highly problematic parasite.
Collapse
Affiliation(s)
- Helene Børretzen Fjørtoft
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | - Frank Nilsen
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
| | | | - Anne Stene
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Ann-Kristin Tveten
- Department of Biological Sciences in Aalesund, Norwegian University of Science and Technology, PO Box 1517, 6025 Aalesund, Norway
| | - Pål Arne Bjørn
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
| | | | - Kevin Alan Glover
- Department of Biology, Sea Lice Research Center, University of Bergen, PO Box 7803, 5020 Bergen, Norway
- Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway
| |
Collapse
|
7
|
Bateman AW, Peacock SJ, Krkošek M, Lewis MA. Migratory hosts can maintain the high-dose/refuge effect in a structured host-parasite system: The case of sea lice and salmon. Evol Appl 2020; 13:2521-2535. [PMID: 33294006 PMCID: PMC7691465 DOI: 10.1111/eva.12984] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 01/13/2023] Open
Abstract
Migration can reduce parasite burdens in migratory hosts, but it connects populations and can drive disease dynamics in domestic species. Farmed salmon are infested by sea louse parasites, often carried by migratory wild salmonids, resulting in a costly problem for industry and risk to wild populations when farms amplify louse numbers. Chemical treatment can control lice, but resistance has evolved in many salmon-farming regions. Resistance has, however, been slow to evolve in the north-east Pacific Ocean, where large wild-salmon populations harbour large sea louse populations. Using a mathematical model of host-macroparasite dynamics, we explored the roles of domestic, wild oceanic and connective migratory host populations in maintaining treatment susceptibility in associated sea lice. Our results show that a large wild salmon population, unexposed to direct infestation by lice from farms; high levels of on-farm treatment; and a healthy migratory host population are all critical to slowing or stopping the evolution of treatment resistance. Our results reproduce the "high-dose/refuge effect," from the agricultural literature, with the added requirement of a migratory host population to maintain treatment susceptibility. This work highlights the role that migratory hosts may play in shared wildlife/livestock disease, where evolution can occur in ecological time.
Collapse
Affiliation(s)
- Andrew W. Bateman
- Pacific Salmon FoundationVancouverBCCanada
- Salmon Coast Field StationSimoom SoundBCCanada
| | - Stephanie J. Peacock
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Biological SciencesUniversity of CalgaryCalgaryABCanada
| | - Martin Krkošek
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Mark A. Lewis
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
- Department of Mathematical and Statistical SciencesUniversity of AlbertaEdmontonABCanada
| |
Collapse
|
8
|
Humble JL, Carmona-Antoñanzas G, McNair CM, Nelson DR, Bassett DI, Egholm I, Bron JE, Bekaert M, Sturm A. Genome-wide survey of cytochrome P450 genes in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837). Parasit Vectors 2019; 12:563. [PMID: 31775848 PMCID: PMC6880348 DOI: 10.1186/s13071-019-3808-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 11/15/2019] [Indexed: 11/24/2022] Open
Abstract
Background The salmon louse (Lepeophtheirus salmonis) infests farmed and wild salmonid fishes, causing considerable economic damage to the salmon farming industry. Infestations of farmed salmon are controlled using a combination of non-medicinal approaches and veterinary drug treatments. While L. salmonis has developed resistance to most available salmon delousing agents, relatively little is known about the molecular mechanisms involved. Members of the cytochrome P450 (CYP) superfamily are typically monooxygenases, some of which are involved in the biosynthesis and metabolism of endogenous compounds, while others have central roles in the detoxification of xenobiotics. In terrestrial arthropods, insecticide resistance can be based on the enhanced expression of CYPs. The reported research aimed to characterise the CYP superfamily in L. salmonis and assess its potential roles in drug resistance. Methods Lepeophtheirus salmonis CYPs were identified by homology searches of the genome and transcriptome of the parasite. CYP transcript abundance in drug susceptible and multi-resistant L. salmonis was assessed by quantitative reverse transcription PCR, taking into account both constitutive expression and expression in parasites exposed to sublethal levels of salmon delousing agents, ecdysteroids and environmental chemicals. Results The above strategy led to the identification of 25 CYP genes/pseudogenes in L. salmonis, making its CYP superfamily the most compact characterised for any arthropod to date. Lepeophtheirus salmonis possesses homologues of a number of arthropod CYP genes with roles in ecdysteroid metabolism, such as the fruit fly genes disembodied, shadow, shade, spook and Cyp18a1. CYP transcript expression did not differ between one drug susceptible and one multi-resistant strain of L. salmonis. Exposure of L. salmonis to emamectin benzoate or deltamethrin caused the transcriptional upregulation of certain CYPs. In contrast, neither ecdysteroid nor benzo[a]pyrene exposure affected CYP transcription significantly. Conclusions The parasite L. salmonis is demonstrated to possess the most compact CYP superfamily characterised for any arthropod to date. The complement of CYP genes in L. salmonis includes conserved CYP genes involved in ecdysteroid biosynthesis and metabolism, as well as drug-inducible CYP genes. The present study does not provide evidence for a role of CYP genes in the decreased susceptibility of the multiresistant parasite strain studied. ![]()
Collapse
Affiliation(s)
- Joseph L Humble
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | | | - Carol M McNair
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - David R Nelson
- Department of Microbiology, University of Tennessee, Memphis, TN, 38163, USA
| | - David I Bassett
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Ingibjørg Egholm
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - James E Bron
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Michaël Bekaert
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Armin Sturm
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| |
Collapse
|
9
|
Staven FR, Nordeide JT, Imsland AK, Andersen P, Iversen NS, Kristensen T. Is Habituation Measurable in Lumpfish Cyclopterus lumpus When Used as Cleaner Fish in Atlantic Salmon Salmo salar Aquaculture? Front Vet Sci 2019; 6:227. [PMID: 31338371 PMCID: PMC6629887 DOI: 10.3389/fvets.2019.00227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/24/2019] [Indexed: 11/13/2022] Open
Abstract
To investigate how lumpfish interact in Atlantic salmon aquaculture, physiological stress responses and changes in behaviour were analysed in experienced and naive lumpfish. Experienced lumpfish (30.2 ± 7.93 g, mean ± SD) coexisted with a commercial scale production unit of Atlantic salmon (1258.5 ± 152.12 g) for 30 to 60 days, while naive lumpfish (38.2 ± 12.37 g) were kept with conspecifics only. Ten trials from each background were tested. For each trial, 10 lumpfish were tagged and transferred to a video monitored experimental tank (2 × 2 × 0.7 m). In each trial, swimming behaviour was mapped for all lumpfish every 60 s in 20 min, 10 min before, and 10 min after the introduction of four Atlantic salmon. Naive lumpfish expressed significantly increased burst swimming activity and maintained longer interspecific distance to Atlantic salmon in comparison with experienced fish. In addition, mean plasma cortisol levels were significantly elevated in naive fish after exposure to Atlantic salmon. We argue that naive lumpfish expressed innate physiological and behavioural stress responses during first encounter with Atlantic salmon, while reduced responses in experienced individuals indicated habituation. The effect from behavioural and physiological stress in newly deployed naive lumpfish-before and during habituation-should be taken account for when lumpfish are introduced in commercial sea cages to improve welfare for the species. In addition, we suggest that habituation could be applicable during the rearing phase to moderate the transition from a simple tank environment with conspecifics only to interspecies interaction with Atlantic salmon in sea cages.
Collapse
Affiliation(s)
- Fredrik R Staven
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway.,Aqua Kompetanse AS, Flatanger, Norway
| | - Jarle T Nordeide
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Albert K Imsland
- Akvaplan-niva Iceland Office, Kópavogur, Iceland.,Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | | | | |
Collapse
|
10
|
Junquera P, Hosking B, Gameiro M, Macdonald A. Benzoylphenyl ureas as veterinary antiparasitics. An overview and outlook with emphasis on efficacy, usage and resistance. Parasite 2019; 26:26. [PMID: 31041897 PMCID: PMC6492539 DOI: 10.1051/parasite/2019026] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/11/2019] [Indexed: 01/17/2023] Open
Abstract
Six benzoylphenyl ureas are currently used in formulations approved as veterinary medicines: diflubenzuron for fly control mainly on cattle, lice and blowfly strike control on sheep, and lice control on farmed salmonids; lufenuron for flea control on dogs and cats and for lice control on farmed salmonids; triflumuron for lice and blowfly strike control on sheep; fluazuron for tick control on cattle; teflubenzuron for lice control on farmed salmon; and novaluron for fly and tick control on cattle and for flea control on dogs. Resistance to diflubenzuron and triflumuron has already been reported for sheep body lice and blowflies, and to fluazuron in cattle ticks. These and other minor veterinary usages, as well as the current status of resistance, are reviewed and perspectives for future opportunities are discussed based on unexplored potentials and threats posed by future resistance development.
Collapse
Affiliation(s)
| | - Barry Hosking
-
Elanco Australasia Pty. Limited Kemps Creek 2178
NSW Australia
| | - Marta Gameiro
-
Elanco Canada Limited 150 Research Lane, Suite 120 Guelph ON
N1G 4T2 Canada
| | - Alicia Macdonald
-
Elanco Canada Limited 150 Research Lane, Suite 120 Guelph ON
N1G 4T2 Canada
| |
Collapse
|
11
|
Saraiva M, Beckmann MJ, Pflaum S, Pearson M, Carcajona D, Treasurer JW, van West P. Exophiala angulospora infection in hatchery-reared lumpfish (Cyclopterus lumpus) broodstock. JOURNAL OF FISH DISEASES 2019; 42:335-343. [PMID: 30632621 PMCID: PMC6378594 DOI: 10.1111/jfd.12940] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/12/2018] [Accepted: 10/12/2018] [Indexed: 06/01/2023]
Abstract
Samples from moribund lumpfish were collected in a marine hatchery in Scotland in 2015. Black nodules were noted on the skin, and gills and fungal hyphae were extensively distributed in musculature and internal organs. Multifocal chronic inflammatory lesions displaced structures in all affected organs. Mortalities commenced on completion of spawning in May and were evenly distributed over the second year in the temperature range 11-15°C. The main systemic infection causing agent was initially identified based on morphological characteristics as an Exophiala species. Ribosomal DNA (rDNA) ITS regions of the isolates were subsequently sequenced confirming the isolates belonged to Exophiala genus. All isolates fell in a single phylogenetic cluster, which is represented by Exophiala angulospora. Fish were treated with either formalin or Bronopol or a combination of both, but there was no effect on the pattern or numbers of mortalities. Isolates were also tested against three different concentrations of Latrunculin A, Amphotericin B and Itraconazole with no success. It is of utmost importance to increase the knowledge on pathogen-host interactions to successfully develop sustainable control methods.
Collapse
Affiliation(s)
- Marcia Saraiva
- Aberdeen Oomycete Laboratory, International Centre for Aquaculture Research and DevelopmentInstitute of Medical SciencesForesterhill, AberdeenUK
| | - Max J. Beckmann
- Aberdeen Oomycete Laboratory, International Centre for Aquaculture Research and DevelopmentInstitute of Medical SciencesForesterhill, AberdeenUK
| | | | | | | | | | - Pieter van West
- Aberdeen Oomycete Laboratory, International Centre for Aquaculture Research and DevelopmentInstitute of Medical SciencesForesterhill, AberdeenUK
| |
Collapse
|
12
|
Urbina MA, Cumillaf JP, Paschke K, Gebauer P. Effects of pharmaceuticals used to treat salmon lice on non-target species: Evidence from a systematic review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 649:1124-1136. [PMID: 30308884 DOI: 10.1016/j.scitotenv.2018.08.334] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/23/2018] [Accepted: 08/24/2018] [Indexed: 05/22/2023]
Abstract
Aquaculture is currently one of the best prospects to help meet the growing need for protein in the human diet. However, aquaculture development and production result in consequences for the environment and also impact other productive activities. Salmon and trout cage culture has required the use of large quantities of pharmaceuticals in order to control outbreaks and the persistence of different pathogens, including sea lice (parasitic copepods), which cause economic losses of around 0.39 € Kg-1 of salmon produced. The pharmaceuticals currently used for the control of sea lice (cypermethrin, deltamethrin, azamethiphos, hydrogen peroxide) are applied by in situ immersion treatments, enclosing net pens using tarpaulin and then bathing fish with the pharmaceutical. After treatment the pharmaceuticals are released into the surrounding environment, exposing non-target species. Although the effects of such pharmaceutical exposure has been studied in some species, to date a systematic and exhaustive review of these potential effects has not yet been performed. In this study, an exhaustive review of the literature evaluating lethal and sub-lethal effects of anti-sea lice pharmaceuticals on non-target crustaceans and bivalves was performed, in order to assess the extent of the effects, toxicity, variables affecting such toxicity and identify potential synergistic effects previously unexplored. Our results show clear negative effects at concentrations lower than those used in treatments against sea lice in all of the species studied. Likewise, this study demonstrates knowledge gaps that need to be addressed in order to improve our understanding of the effects of these pharmaceuticals on non-target species, ecosystems in general and other productive activities.
Collapse
Affiliation(s)
- M A Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Chile.
| | - J P Cumillaf
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile; Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Los Pinos s/n, Balneario Pelluco, Puerto Montt, Chile
| | - K Paschke
- Instituto de Acuicultura, Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Chile
| | - P Gebauer
- Centro i~mar, Universidad de Los Lagos, Camino Chinquihue Km 6, Puerto Montt, Chile
| |
Collapse
|
13
|
Harðardóttir HM, Male R, Nilsen F, Eichner C, Dondrup M, Dalvin S. Chitin synthesis and degradation in Lepeophtheirus salmonis: Molecular characterization and gene expression profile during synthesis of a new exoskeleton. Comp Biochem Physiol A Mol Integr Physiol 2019; 227:123-133. [DOI: 10.1016/j.cbpa.2018.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
|
14
|
Zhang L, Gionfriddo E, Acquaro V, Pawliszyn J. Direct immersion solid-phase microextraction analysis of multi-class contaminants in edible seaweeds by gas chromatography-mass spectrometry. Anal Chim Acta 2018; 1031:83-97. [DOI: 10.1016/j.aca.2018.05.066] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 10/16/2022]
|
15
|
Agusti-Ridaura C, Dondrup M, Horsberg TE, Leong JS, Koop BF, Bravo S, Mendoza J, Kaur K. Caligus rogercresseyi acetylcholinesterase types and variants: a potential marker for organophosphate resistance. Parasit Vectors 2018; 11:570. [PMID: 30376873 PMCID: PMC6208076 DOI: 10.1186/s13071-018-3151-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/14/2018] [Indexed: 12/17/2022] Open
Abstract
Background Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other organophosphates were previously used. In 2014, reduced sensitivity to azamethiphos was detected in the Los Lagos Region using bioassays. The main target of organophosphates is the enzyme acetylcholinesterase (AChE). Mutations in the AChE gene are the main cause of organophosphate resistance in arthropods, including other sea lice. In the present study, we aimed to characterize C. rogercresseyi AChE(s) gene(s) and to study the association between AChE variants and azamethiphos resistance in this sea louse species. Methods Samples of adult male and female C. rogercresseyi were collected in the Los Lagos Region in 2014. Twenty-four hour exposure bioassays with azamethiphos were performed to select sensitive and resistant lice. The full-length cDNA coding sequences encoding for two AChEs in C. rogercresseyi were molecularly characterized. One of the AChE genes was screened by direct sequencing in the azamethiphos-selected lice to search for variants. An additional louse sampling was performed before and after an azamethiphos treatment in the field in 2017 to validate the findings. Results The molecular analysis revealed two putative AChEs in C. rogercresseyi. In silico analysis and 3D modelling of the protein sequences identified both of them as invertebrate AChE type 1; they were named C. rogercresseyi AChE1a and 1b. AChE1a had the characteristics of the main synaptic AChE, while AChE1b lacked some of the important amino acids of a typical AChE. A missense change found in the main synaptic AChE (1a), F318F/V (F290 in Torpedo californica), was associated with survival of C. rogercresseyi at high azamethiphos concentrations (bioassays and field treatment). The amino acid change was located in the acyl pocket of the active-site gorge of the protein. Conclusions The present study demonstrates the presence of two types of AChE1 genes in C. rogercresseyi. Although enzymatic assays are needed, AChE1a is most probably the main synaptic AChE. The function of AChE1b is unknown, but evidence points to a scavenger role. The AChE1a F/V318 variant is most probably involved in organophosphate resistance, and can be a good marker for resistance monitoring. Electronic supplementary material The online version of this article (10.1186/s13071-018-3151-7) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Celia Agusti-Ridaura
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway.
| | - Michael Dondrup
- Department of Informatics, University of Bergen, Sea Lice Research Centre, Thormøhlensgate 55, N-5008, Bergen, Norway
| | - Tor E Horsberg
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway
| | - Jong S Leong
- Biology Department, Centre for Biomedical Research, University of Victoria, Station CSC, PO Box 1700, Victoria, BC, V8W 2Y2, Canada
| | - Ben F Koop
- Biology Department, Centre for Biomedical Research, University of Victoria, Station CSC, PO Box 1700, Victoria, BC, V8W 2Y2, Canada
| | - Sandra Bravo
- Universidad Austral de Chile, Casilla 1327, Puerto Montt, Chile
| | - Julio Mendoza
- Cermaq Chile, Diego Portales 2000, Puerto Montt, Chile
| | - Kiranpreet Kaur
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Sea Lice Research Centre, Postboks 369 Sentrum, Oslo, NO-0102, Norway
| |
Collapse
|
16
|
Marín SL, Mancilla J, Hausdorf MA, Bouchard D, Tudor MS, Kane F. Sensitivity assessment of sea lice to chemotherapeutants: Current bioassays and best practices. JOURNAL OF FISH DISEASES 2018; 41:995-1003. [PMID: 29251354 DOI: 10.1111/jfd.12768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/27/2017] [Accepted: 11/15/2017] [Indexed: 06/07/2023]
Abstract
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.
Collapse
Affiliation(s)
- S L Marín
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Puerto Montt, Chile
| | - J Mancilla
- PhD Aquaculture Sciences, Universidad Austral de Chile, Puerto Montt, Chile
| | | | - D Bouchard
- University of Maine Animal Health Laboratory, University of Maine, Orono, ME, USA
| | - M S Tudor
- University of Maine Animal Health Laboratory, University of Maine, Orono, ME, USA
| | - F Kane
- Aquaculture Section, Marine Institute, Galway, Ireland
| |
Collapse
|
17
|
Nelson EJ, Robinson SMC, Feindel N, Sterling A, Byrne A, Pee Ang K. Horizontal and vertical distribution of sea lice larvae (Lepeophtheirus salmonis) in and around salmon farms in the Bay of Fundy, Canada. JOURNAL OF FISH DISEASES 2018; 41:885-899. [PMID: 29159846 DOI: 10.1111/jfd.12692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/08/2017] [Accepted: 06/28/2017] [Indexed: 06/07/2023]
Abstract
The sea louse, Lepeophtheirus salmonis, is parasitic to salmonid species in the Northern Hemisphere and has become a widespread biological and economic problem for the salmon farming industry. A better understanding is needed of their spatial distribution and early life history to disrupt the life cycle of the sea louse. In this study, sea lice larval densities within salmon farms, between salmon farms and reference sites, and at various depths were quantified using both plankton pumps and plankton nets. Farm sites exhibited significantly higher densities than reference sites; however, these densities dropped an order of magnitude at a distance of 100 m from the cages. The majority of the larvae captured in the study were nauplii (93%), and densities ranged from 0 to 10 larvae/m3 . Free-swimming sea lice larvae were found to exhibit a diel cycle where nauplii larvae were in deeper waters (10-17 m) during the day and in surface waters (1-6 m) during the night. The results of this study suggest that the early life-history stages of sea lice originate from and may remain close to active salmon farms, creating a self-sustaining population.
Collapse
Affiliation(s)
- E J Nelson
- Fisheries and Oceans Canada, St. Andrews, NB, Canada
| | | | - N Feindel
- Department of Fisheries and Aquaculture, Shelburne, NS, Canada
| | | | - A Byrne
- Department of Geography, University of Victoria, Victoria, BC, Canada
| | - K Pee Ang
- Cooke Aquaculture Inc., Back Bay, NB, Canada
| |
Collapse
|
18
|
Marín SL, González MP, Madariaga ST, Mancilla M, Mancilla J. Response of Caligus rogercresseyi (Boxshall & Bravo, 2000) to treatment with Hydrogen Peroxide: Recovery of parasites, fish infestation and egg viability under experimental conditions. JOURNAL OF FISH DISEASES 2018; 41:861-873. [PMID: 28921553 DOI: 10.1111/jfd.12691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/27/2017] [Accepted: 06/23/2017] [Indexed: 06/07/2023]
Abstract
Hydrogen peroxide (HP) is used to remove C. rogercresseyi from fish but little is known about its effect on this species. This study determined EC50 and concentration immobilizing 100% of specimens, capacity of parasites exposed to HP to recover and infest fish, and effect on survival into the copepodid stage. EC50 and concentration immobilizing 100% of specimens were estimated by exposing parasites for 20 min to 11 concentrations and evaluating effect at 1 and 24 h post-exposure. Capacity to recover and infest fish, and survival into copepodid were evaluated by exposing parasites and eggs to HP for 20 min. Recovery and fish infestation were evaluated at 25 and 24 h post-exposure, respectively. Eggs were grown until control reached the copepodid stage and survival calculated. EC50 was 709.8 ppm.100% immobilization was obtained at 825 ppm. Male and female recover 0.5 and 1 h post-exposure, respectively. Percentage of parasites exposed and not exposed to HP that were recovered on fish was not significantly different. Survival to copepodid was lower in those exposed to HP. HP effect is greater on copepodids, but 100% of the mobile stages are immobilized under 825 ppm causing detachment from fish and potentially driven away, reducing infestation risk.
Collapse
Affiliation(s)
- S L Marín
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
| | - M P González
- PhD Program in Aquaculture Sciences, Universidad Austral de Chile, Puerto Montt, Chile
| | - S T Madariaga
- Centro de Docencia Superior en Ciencias Básicas, Universidad Austral de Chile, Puerto Montt, Chile
| | - M Mancilla
- Institute of Aquaculture, Universidad Austral de Chile, Puerto Montt, Chile
| | - J Mancilla
- PhD Program in Aquaculture Sciences, Universidad Austral de Chile, Puerto Montt, Chile
| |
Collapse
|
19
|
Deltamethrin resistance in the salmon louse, Lepeophtheirus salmonis (Krøyer): Maternal inheritance and reduced apoptosis. Sci Rep 2018; 8:8450. [PMID: 29855496 PMCID: PMC5981211 DOI: 10.1038/s41598-018-26420-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 05/08/2018] [Indexed: 01/15/2023] Open
Abstract
Resistance towards deltamethrin (DMT) in the crustacean ectoparasite Lepeophtheirus salmonis (Caligidae) is a problem on fish farms lining the North Atlantic Ocean. Two Norwegian strains with different susceptibility towards DMT were crossed in the parental generation (P0), females from a sensitive strain were crossed with males from a resistant strain and vice versa. Individual susceptibility towards DMT was assessed in the second filial generation (F2). DMT resistance was only found in F2 descendants when the P0 females were from the resistant strain, pointing to maternal inheritance. Since maternal inheritance might be linked to the mitochondrial (mt) genome, the nucleotide sequences and the gene expressions of mt-genes were analysed. Twenty non-synonymous single nucleotide polymorphisms (SNPs) were identified in mt-transcripts from resistant F2 parasites, including SNPs in two cytochrome C oxidase subunits (COX1 and COX3) and two subunits of the NADH dehydrogenase complex (ND1 and ND5) previously linked to DMT resistance in the salmon louse. Differential expression analysis between the sensitive and resistant strain revealed strain effect in seven out of twelve mt-genes. The current study also show that DNA fragmentation (indicating apoptosis) was affected by DMT exposure in skeletal muscle tissue and that resistant parasites undergo less apoptosis than sensitive parasites.
Collapse
|
20
|
Arriagada G, Sanchez J, Stryhn H, Vanderstichel R, Campistó JL, Ibarra R, St-Hilaire S. A multivariable assessment of the spatio-temporal distribution of pyrethroids performance on the sea lice Caligus rogercresseyi in Chile. Spat Spatiotemporal Epidemiol 2018; 26:1-13. [PMID: 30390925 DOI: 10.1016/j.sste.2018.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 01/12/2018] [Accepted: 04/27/2018] [Indexed: 10/17/2022]
Abstract
Synthetic pyrethroids have been widely used in Chile to control the sea lice Caligus rogercresseyi, a major ectoparasite of farmed salmon. Although resistance of C. rogercresseyi to pyrethroids has been reported in Chile, there is no information regarding the geographic extent of this problem. In this study we explored the spatial and temporal variation of C. rogercresseyi's response to pyrethroids in Chile from 2012 to 2013. We modeled lice abundance one week after treatment with a linear mixed-effects regression, and then we performed spatial and spatio-temporal cluster analyses on farm-level effects and on treatment-level residuals, respectively. Results indicate there were two areas where the post-treatment lice counts were significantly higher than in the rest of the study area. These spatial clusters remained even once we adjusted for environmental and management predictors, suggesting unmeasured factors (e.g. resistance) were causing the clustering. Further investigation should be carried out to confirm this hypothesis.
Collapse
Affiliation(s)
- Gabriel Arriagada
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada.
| | - Javier Sanchez
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
| | - Henrik Stryhn
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
| | - Raphaël Vanderstichel
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
| | - José Luis Campistó
- Department of Fish Health, Instituto Tecnológico del Salmón, Av. Juan Soler Manfredini 41, Of. 1802, Puerto Montt, Chile
| | - Rolando Ibarra
- Department of Fish Health, Instituto Tecnológico del Salmón, Av. Juan Soler Manfredini 41, Of. 1802, Puerto Montt, Chile
| | - Sophie St-Hilaire
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
| |
Collapse
|
21
|
Jacobs A, De Noia M, Praebel K, Kanstad-Hanssen Ø, Paterno M, Jackson D, McGinnity P, Sturm A, Elmer KR, Llewellyn MS. Genetic fingerprinting of salmon louse (Lepeophtheirus salmonis) populations in the North-East Atlantic using a random forest classification approach. Sci Rep 2018; 8:1203. [PMID: 29352185 PMCID: PMC5775277 DOI: 10.1038/s41598-018-19323-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/17/2017] [Indexed: 12/13/2022] Open
Abstract
Caligid sea lice represent a significant threat to salmonid aquaculture worldwide. Population genetic analyses have consistently shown minimal population genetic structure in North Atlantic Lepeophtheirus salmonis, frustrating efforts to track louse populations and improve targeted control measures. The aim of this study was to test the power of reduced representation library sequencing (IIb-RAD sequencing) coupled with random forest machine learning algorithms to define markers for fine-scale discrimination of louse populations. We identified 1286 robustly supported SNPs among four L. salmonis populations from Ireland, Scotland and Northern Norway. Only weak global structure was observed based on the full SNP dataset. The application of a random forest machine-learning algorithm identified 98 discriminatory SNPs that dramatically improved population assignment, increased global genetic structure and resulted in significant genetic population differentiation. A large proportion of SNPs found to be under directional selection were also identified to be highly discriminatory. Our data suggest that it is possible to discriminate between nearby L. salmonis populations given suitable marker selection approaches, and that such differences might have an adaptive basis. We discuss these data in light of sea lice adaption to anthropogenic and environmental pressures as well as novel approaches to track and predict sea louse dispersal.
Collapse
Affiliation(s)
- A Jacobs
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - M De Noia
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - K Praebel
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037, Tromsø, Norway
| | | | - M Paterno
- Department of Biology, University of Padova, Padova, Italy
| | | | - P McGinnity
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
| | - A Sturm
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - K R Elmer
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - M S Llewellyn
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.
| |
Collapse
|
22
|
Ljungfeldt LER, Quintela M, Besnier F, Nilsen F, Glover KA. A pedigree-based experiment reveals variation in salinity and thermal tolerance in the salmon louse, Lepeophtheirus salmonis. Evol Appl 2017; 10:1007-1019. [PMID: 29151856 PMCID: PMC5680634 DOI: 10.1111/eva.12505] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 06/05/2017] [Indexed: 11/29/2022] Open
Abstract
The salmon louse is a highly abundant ectoparasitic copepod of salmonids in the North Pacific and Atlantic. Widespread and rapid development of resistance to chemical agents used to delouse salmonids on marine farms is now threatening the continued development of the aquaculture industry and have served as a potent catalyst for the development of alternative pest management strategies. These include freshwater and warm-water treatments to which the louse is sensitive. However, given the well-documented evolutionary capacity of this species, the risk of developing tolerance towards these environmental treatments cannot be dismissed. Two common-garden experiments were performed using full-sibling families of lice identified by DNA parentage testing to investigate whether one of the fundamental premises for evolution, in this context genetic variation in the capacity of coping with fresh or warm water, exists within this species. Significant differences in survival were observed among families in both experiments, although for the salinity experiment, it was not possible to unequivocally disentangle background mortality from treatment-induced mortality. Thus, our data demonstrate genetic variation in tolerance of warm water and are suggestive of genetic variation in salinity tolerance. We conclude that extensive use of these environmental-based treatments to delouse salmonids on commercial farms may drive lice towards increased tolerance.
Collapse
Affiliation(s)
| | | | | | - Frank Nilsen
- Sea Lice Research CentreDepartment of BiologyUniversity of BergenBergenNorway
| | - Kevin Alan Glover
- Institute of Marine ResearchBergenNorway
- Sea Lice Research CentreDepartment of BiologyUniversity of BergenBergenNorway
| |
Collapse
|
23
|
The Phe362Tyr mutation conveying resistance to organophosphates occurs in high frequencies in salmon lice collected from wild salmon and trout. Sci Rep 2017; 7:14258. [PMID: 29079820 PMCID: PMC5660183 DOI: 10.1038/s41598-017-14681-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 10/13/2017] [Indexed: 12/02/2022] Open
Abstract
The parasitic salmon louse, and its resistance to chemical delousing agents, represents one of the largest challenges to the salmon aquaculture industry. We genotyped lice sampled from wild salmon and sea trout throughout Norway with the recently identified Phe362Tyr mutation that conveys resistance to organophosphates. These results were compared to data from lice sampled on farmed salmon in the same regions. The resistant (R) allele was observed in salmon lice from wild salmon and sea trout throughout Norway, although its frequency was highest in farming-intense regions. In most regions, the frequency of the R allele was higher in lice collected from wild sea trout than wild Atlantic salmon, and in all regions, the frequency of the R allele was similar in lice collected from wild sea trout and farmed Atlantic salmon. The R allele is only selected for in fish-farms where organophosphates are used for delousing. Therefore, our results suggest extensive exchange of lice between farmed and wild hosts, and indicate that in farming-dense regions in Norway, aquaculture represents a major driver of salmon louse population structure. Finally, these data suggest that the wild hosts within the regions studied will not delay the spread of resistance when organophosphates are used.
Collapse
|
24
|
McEwan GF, Groner ML, Burnett DL, Fast MD, Revie CW. Managing aquatic parasites for reduced drug resistance: lessons from the land. J R Soc Interface 2017; 13:rsif.2016.0830. [PMID: 28003529 DOI: 10.1098/rsif.2016.0830] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/28/2016] [Indexed: 11/12/2022] Open
Abstract
Atlantic salmon farming is one of the largest aquaculture industries in the world. A major problem in salmon farms is the sea louse ectoparasite Lepeophtheirus salmonis, which can cause stress, secondary infection and sometimes mortality in the salmon host. Sea lice have substantial impacts on farm economics and potentially nearby wild salmonid populations. The most common method of controlling sea louse infestations is application of chemicals. However, most farming regions worldwide have observed resistance to the small set of treatment chemicals that are available. Despite this, there has been little investigation of treatment strategies for managing resistance in aquaculture. In this article, we compare four archetypical treatment strategies inspired by agriculture, where the topic has a rich history of study, and add a fifth strategy common in aquaculture. We use an agent-based model (ABM) to simulate these strategies and their varying applications of chemicals over time and space. We analyse the ABM output to compare how the strategies perform in controlling louse abundance, number of treatments required and levels of resistance in the sea louse population. Our results indicated that among the approaches considered applying chemicals in combination was the most effective over the long term.
Collapse
Affiliation(s)
- Gregor F McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Maya L Groner
- Departments of Fisheries Management and Aquatic Health Sciences, Virginia Institute of Marine Science, 1375 Greate Road, Gloucester Point, VA 23062-1346, USA
| | - Danielle L Burnett
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Mark D Fast
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Crawford W Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| |
Collapse
|
25
|
The mechanism (Phe362Tyr mutation) behind resistance in Lepeophtheirus salmonis pre-dates organophosphate use in salmon farming. Sci Rep 2017; 7:12349. [PMID: 28955050 PMCID: PMC5617835 DOI: 10.1038/s41598-017-12384-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 09/07/2017] [Indexed: 11/29/2022] Open
Abstract
The salmon louse is an ectoparasitic copepod of salmonids in the marine environment, and represents a global challenge to salmon aquaculture. A major issue is the reliance of the industry on a limited number of chemicals to delouse salmonids on farms, and the high levels of resistance that lice have developed to all of these agents. However, for most of these chemicals, resistance and dispersal mechanisms are unknown. We recently demonstrated that the Phe362Tyr mutation is the primary cause of organophosphate resistance in lice collected on Norwegian farms. In the present study, we genotyped >2000 lice collected throughout the entire North Atlantic in the period 1998–2016, using Phe362Tyr and nine tightly linked SNPs. Our results showed that the Phe362Tyr mutation is strongly linked to lice survival following chemical treatment on farms located throughout the North Atlantic, demonstrating for the first time, that this mutation represents the primary mechanism for organophosphate resistance in salmon lice across the North Atlantic. Additionally, we observed multiple and diverse high frequency haplotypes linked with the allele conveying resistance to organophosphate. We, therefore, conclude that Phe362Tyr is not a de novo mutation, but probably existed in salmon lice before the introduction of organophosphates in commercial aquaculture.
Collapse
|
26
|
Hansen BH, Hallmann A, Altin D, Jenssen BM, Ciesielski TM. Acute hydrogen peroxide (H 2O 2) exposure does not cause oxidative stress in late-copepodite stage of Calanus finmarchicus. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2017; 80:820-829. [PMID: 28777041 DOI: 10.1080/15287394.2017.1352182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Use of hydrogen peroxide (H2O2) for removal of salmon lice in the aquaculture industry has created concern that non-target organisms might be affected during treatment scenarios. The aim of the present study was to examine the potential for H2O2 to produce oxidative stress and reduce survival in one of the most abundant zooplankton species in Norwegian coastal areas, the copepod Calanus finmarchicus. Copepods were subjected to two 96-hr tests: (1) acute toxicity test where mortality was determined and (2) treated copepods were exposed to concentrations below the No Observed Effect Concentration (0.75 mg/L) H2O2 and analyzed for antioxidant enzyme activities, as well as levels of glutathione (GSH) and malondialdehyde (MDA). Compared to available and comparable LC50 values from the literature, our results suggest that C. finmarchicus is highly sensitive to H2O2. However, 96-hr exposure of C. finmarchicus to 0.75 mg H2O2/L did not significantly affect the antioxidant systems even though the concentration is just below the level where mortality is expected. Data suggest that aqueous H2O2 exposure did not cause cellular accumulation with associated oxidative stress, but rather produced acute effects on copepod surface (carapace). Further investigation is required to ensure that aqueous exposure during H2O2 treatment in salmon fish farms does not exert adverse effects on local non-target crustacean species and populations. In particular, studies on copepod developmental stages with a more permeable carapace are warranted.
Collapse
Affiliation(s)
| | - Anna Hallmann
- b Department of Pharmaceutical Biochemistry , Medical University of Gdańsk , Gdańsk , Poland
| | | | - Bjørn Munro Jenssen
- d Norwegian University of Science and Technology , Department of Biology , Trondheim , Norway
| | - Tomasz M Ciesielski
- d Norwegian University of Science and Technology , Department of Biology , Trondheim , Norway
| |
Collapse
|
27
|
Godwin SC, Dill LM, Krkošek M, Price MHH, Reynolds JD. Reduced growth in wild juvenile sockeye salmon Oncorhynchus nerka infected with sea lice. JOURNAL OF FISH BIOLOGY 2017; 91:41-57. [PMID: 28556094 DOI: 10.1111/jfb.13325] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/29/2017] [Indexed: 06/07/2023]
Abstract
Daily growth rings were examined in the otoliths of wild juvenile sockeye salmon Oncorhynchus nerka to determine whether infection by ectoparasitic sea lice Caligus clemensi and Lepeophtheirus salmonis was associated with reduced host body growth, an important determinant of survival. Over 98% of the sea lice proved to be C. clemensi and the fish that were highly infected grew more slowly than uninfected individuals. Larger fish also grew faster than smaller fish. Finally, there was evidence of an interaction between body size and infection status, indicating the potential for parasite-mediated growth divergence.
Collapse
Affiliation(s)
- S C Godwin
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - L M Dill
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - M Krkošek
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Salmon Coast Field Station, Simoom Sound, BC, V0P 1S0, Canada
| | - M H H Price
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- SkeenaWild Conservation Trust, Terrace, BC, V8G 1P2, Canada
| | - J D Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| |
Collapse
|
28
|
Mennerat A, Ugelvik MS, Håkonsrud Jensen C, Skorping A. Invest more and die faster: The life history of a parasite on intensive farms. Evol Appl 2017; 10:890-896. [PMID: 29151880 PMCID: PMC5680424 DOI: 10.1111/eva.12488] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/11/2017] [Indexed: 01/05/2023] Open
Abstract
Organisms are expected to respond to alterations in their survival by evolutionary changes in their life history traits. As agriculture and aquaculture have become increasingly intensive in the past decades, there has been growing interest in their evolutionary effects on the life histories of agri‐ and aquacultural pests, parasites, and pathogens. In this study, we used salmon lice (Lepeophtheirus salmonis) to explore how modern farming might have affected life history evolution in parasites. We infected salmon hosts with lice from either farmed or unfarmed locations, and monitored life history traits of those parasites in laboratory conditions. Our results show that compared to salmon lice from areas unaffected by salmon farming, those from farmed areas produced more eggs in their first clutch, and less eggs later on; they achieved higher infestation intensities in early adulthood, but suffered higher adult mortality. These results suggest that salmon lice on farms may have been selected for increased investment in early reproduction, at the expense of later fecundity and survival. This call for further empirical studies of the extent to which farming practices may alter the virulence of agricultural parasites.
Collapse
Affiliation(s)
- Adèle Mennerat
- Department of Biology University of Bergen Bergen Norway.,Ecologie et Dynamique des Systèmes Anthropisés (FRE 3498) CNRS/Université de Picardie Jules Verne Amiens France
| | | | | | - Arne Skorping
- Department of Biology University of Bergen Bergen Norway
| |
Collapse
|
29
|
Scholz F, Fringuelli E, Bolton-Warberg M, Marcos-López M, Mitchell S, Prodhol P, Moffet D, Savage P, Murphy O'Sullivan S, O Connor I, McCarthy E, Rodger HD. First record of Tetramicra brevifilum in lumpfish (Cyclopterus lumpus, L.). JOURNAL OF FISH DISEASES 2017; 40:757-771. [PMID: 27716959 DOI: 10.1111/jfd.12554] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
A microsporidian species with 98.3-98.4% nucleotide identity to Tetramicra brevifilum (Journal of Fish Diseases, 3, 1980, 495) was diagnosed in lumpfish (Cyclopterus lumpus, L.) broodstock held at a breeding and rearing facility in western Ireland. The fish were wild-caught from the west coast of Ireland, and the first case was diagnosed one year after capture. Clinical signs included severe bloating, lethargy, exophthalmos, anorexia, white patches on the cornea and externally visible parasitic cysts on skin and fins. Necropsy revealed severe ascites, white nodules and vacuoles in all the internal organs and partial liquefaction of the skeletal muscle. On histological examination, microsporidian xenomas were observed in all internal organs, the skin, skeletal muscle, gills and the eyes. The microsporidian species was identified by molecular analysis and transmission electron microscopy. This is the first record of T. brevifilum infecting lumpfish, and the disease is considered to be of potential significance to the rising aquaculture industry of this species.
Collapse
Affiliation(s)
- F Scholz
- Vet-Aqua International, Oranmore Business Park, Oranmore, Co. Galway, Ireland
- Galway-Mayo Institute of Technology, Marine and Freshwater Research Centre, Galway, Ireland
| | - E Fringuelli
- Veterinary Sciences Division, Agri-food and Biosciences Institute of Northern Ireland, Stormont, Belfast, UK
| | - M Bolton-Warberg
- Carna Research Station, Ryan Institute, NUIG, Carna, Co. Galway, Ireland
| | - M Marcos-López
- Vet-Aqua International, Oranmore Business Park, Oranmore, Co. Galway, Ireland
- Galway-Mayo Institute of Technology, Marine and Freshwater Research Centre, Galway, Ireland
| | - S Mitchell
- Vet-Aqua International, Oranmore Business Park, Oranmore, Co. Galway, Ireland
| | | | - D Moffet
- Veterinary Sciences Division, Agri-food and Biosciences Institute of Northern Ireland, Stormont, Belfast, UK
| | - P Savage
- Veterinary Sciences Division, Agri-food and Biosciences Institute of Northern Ireland, Stormont, Belfast, UK
| | | | - I O Connor
- Galway-Mayo Institute of Technology, Marine and Freshwater Research Centre, Galway, Ireland
| | - E McCarthy
- Galway-Mayo Institute of Technology, Marine and Freshwater Research Centre, Galway, Ireland
| | - H D Rodger
- Vet-Aqua International, Oranmore Business Park, Oranmore, Co. Galway, Ireland
| |
Collapse
|
30
|
Long noncoding RNAs: Unexplored players in the drug response of the sea louse Caligus rogercresseyi. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.aggene.2017.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
31
|
Myhre Jensen E, Sevatdal S, Bakke MJ, Kaur K, Horsberg TE. A selection study on a laboratory-designed population of salmon lic (Lepeophtheirus salmonis) using organophosphate and pyrethroid pesticides. PLoS One 2017; 12:e0178068. [PMID: 28531206 PMCID: PMC5439706 DOI: 10.1371/journal.pone.0178068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/08/2017] [Indexed: 11/30/2022] Open
Abstract
Resistance towards antiparasitic agents in the salmon louse (Lepeophtheirus salmonis) is a widespread problem along the Norwegian coast, reducing treatments efficacies and slowing down the envisioned expansion of Norwegian salmon production. The present study was conducted in order to assess the efficacies of two of the most widely used anti-parasitic substances–azamethiphos and deltamethrin–as well as assessing the benefit of having a resistant genotype compared to being fully sensitive when exposed to one of these substances. Atlantic salmon were exposed to a mix of salmon lice copepodids from a fully sensitive, a double resistant and a multi-resistant strain. Once the lice reached pre-adult stages, one group was exposed to 100 μg/L azamethiphos for 60 minutes, the other to 2 μg/L deltamethrin for 30 minutes, and the last was kept in a seawater control. Detached lice were collected at a series of time points following exposure, and all lice (immobilized and surviving) were analysed for both pyrethroid (sensitive “S” and resistant “R”) and azamethiphos (fully sensitive “SS”, heterozygous resistant “RS” and fully resistant “RR”) resistance markers. We found that the efficacies of deltamethrin on parasites with genotype S and R were 70.3 and 13.2%, respectively. The overall efficacy of the deltamethrin treatment was 32.3%. The efficacies of azamethiphos on parasites with genotype SS, RS and RR were 100, 80 and 19.1%, respectively. The overall efficacy of the azamethiphos treatment was 80.4%. Survival analyses revealed that the median survival time in deltamethrin-sensitive and–resistant parasites were 16.8 and >172 hours, respectively. The differences were even more pronounced in the azamethiphos-treated group, where SS, RS and RR parasites survived for 0.26, 6.6 and >172 hours, respectively. The substantial differences in survival between sensitive and resistant lice following treatment demonstrate the ability of medicinal treatments to drive genetic selection towards a much more resistant salmon lice population within a very short time span if there is no influx of sensitive genotypes.
Collapse
Affiliation(s)
- Elena Myhre Jensen
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Sea Lice Research Centre, Oslo, Norway
- * E-mail:
| | | | - Marit Jørgensen Bakke
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Sea Lice Research Centre, Oslo, Norway
| | - Kiranpreet Kaur
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Sea Lice Research Centre, Oslo, Norway
| | - Tor Einar Horsberg
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Sea Lice Research Centre, Oslo, Norway
| |
Collapse
|
32
|
Carmona-Antoñanzas G, Humble JL, Carmichael SN, Heumann J, Christie HR, Green DM, Bassett DI, Bron JE, Sturm A. Time-to-response toxicity analysis as a method for drug susceptibility assessment in salmon lice. AQUACULTURE (AMSTERDAM, NETHERLANDS) 2016; 464:570-575. [PMID: 27812230 PMCID: PMC5035062 DOI: 10.1016/j.aquaculture.2016.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 06/06/2023]
Abstract
UNLABELLED The salmon louse Lepeophtheirus salmonis (Krøyer, 1837) is an ectoparasite causing infections of wild and farmed Atlantic salmon (Salmo salar L.) in the Northern hemisphere. While L. salmonis control at commercial mariculture sites increasingly employs non-medicinal approaches, such as cage designs reducing infection rates and biological control through cleaner fish, anti-parasitic drugs are still a requirement for effective fish health care. With only a limited range of salmon delousing agents available, all of which have been in use for more than a decade, drug resistance formation has been reported for different products. Successful resistance management requires reliable susceptibility assessment, which is usually achieved through L. salmonis bioassays. These tests involve the exposure of parasites to different drug concentrations and require significant numbers of suitable L. salmonis stages. The present study reports an alternative bioassay that is based on time-to-response toxicity analyses and can be carried out with limited parasite numbers. The assay determines the median effective time (ET50), i.e., the time required until impaired swimming and/or attachment behaviour becomes apparent in 50% of parasites, by conducting repeated examinations of test animals starting at the time point where exposure to a set drug concentration commences. This experimental approach further allows the estimation of the apparent drug susceptibility of individual L. salmonis by determining their time to response, which may prove useful in experiments designed to elucidate associations between genetic factors and the drug susceptibility phenotype of parasites. Three laboratory strains of L. salmonis differing in susceptibility to emamectin benzoate were characterised using standard 24 h bioassays and time-to-response toxicity assays. While both the median effective concentration (EC50) and the ET50 showed variability between experimental repeats, both types of bioassay consistently discriminated susceptible and drug-resistant L. salmonis laboratory strains. STATEMENT OF RELEVANCE Infections by sea lice cause significant costs to the global salmon farming industry, which have been estimated to exceed €300 million per year worldwide. Control of sea lice still relies to a significant extent on chemical delousing; however, chemical control is threatened by resistance formation. Resistance can be combated by rotation between different drugs and strategic implementation of non-medicinal strategies. However, resistance management requires reliable and feasible methods of susceptibility assessment. The present study is a technical note introducing a novel approach to susceptibility assessments in sea lice. The method can be applied in susceptibility assessments on farms, where it offers the advantage of a reduced requirement of parasites for testing. In addition, the novel method allows deriving the times of parasite require to show a response after drug treatment has started, thus providing a variable characterizing the drug susceptibility phenotype of individual parasites. Accordingly, the bioassay approach presented here will be useful for studies aiming at unravelling the genetic determinants of drug resistance.
Collapse
Affiliation(s)
- Greta Carmona-Antoñanzas
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Joseph L. Humble
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Stephen N. Carmichael
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Jan Heumann
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Hayden R.L. Christie
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Darren M. Green
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - David I. Bassett
- Marine Environmental Research Laboratory, University of Stirling, Machrihanish, Argyll, PA28 6PZ, Scotland, UK
| | - James E. Bron
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Armin Sturm
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| |
Collapse
|
33
|
Clark W, Leclercq E, Migaud H, Nairn J, Davie A. Isolation, identification and characterisation of ballan wrasse Labrus bergylta plasma pigment. JOURNAL OF FISH BIOLOGY 2016; 89:2070-2084. [PMID: 27501866 DOI: 10.1111/jfb.13106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 07/05/2016] [Indexed: 06/06/2023]
Abstract
This study confirmed that observations of blue-green colouration in plasma fractions of the ballan wrasse Labrus bergylta were caused by the linear tetra-pyrrole biliverdin and that the molecule was of the physiologically relevant IXα isomer. Accumulation appears driven by chromogenic association with an unknown protein moiety which precludes enzymatic reduction and would suggest active management. It was demonstrated that the pigment did not fluctuate relative to ontogeny, or indeed binary gender in the species of interest, but mobilisation and depletion in the subset of individuals undergoing sex change at the time of study supports a potential association with gender inversion processes. It is of note that although biliverdin does have some effect on external colouration, the evidence is indicative that crypsis is a supplementary function thus other factors must be considered.
Collapse
Affiliation(s)
- W Clark
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, U.K
| | - E Leclercq
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, U.K
| | - H Migaud
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, U.K
| | - J Nairn
- School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TS, Scotland, U.K
| | - A Davie
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, U.K..
| |
Collapse
|
34
|
Predicting the effectiveness of depth-based technologies to prevent salmon lice infection using a dispersal model. Prev Vet Med 2016; 129:48-57. [DOI: 10.1016/j.prevetmed.2016.05.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/01/2016] [Accepted: 05/20/2016] [Indexed: 11/19/2022]
|
35
|
Jansen PA, Grøntvedt RN, Tarpai A, Helgesen KO, Horsberg TE. Surveillance of the Sensitivity towards Antiparasitic Bath-Treatments in the Salmon Louse (Lepeophtheirus salmonis). PLoS One 2016; 11:e0149006. [PMID: 26889677 PMCID: PMC4759459 DOI: 10.1371/journal.pone.0149006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 01/26/2016] [Indexed: 11/18/2022] Open
Abstract
The evolution of drug resistant parasitic sea lice is of major concern to the salmon farming industry worldwide and challenges sustainable growth of this enterprise. To assess current status and development of L. salmonis sensitivity towards different pesticides used for parasite control in Norwegian salmon farming, a national surveillance programme was implemented in 2013. The programme aims to summarize data on the use of different pesticides applied to control L. salmonis and to test L. salmonis sensitivity to different pesticides in farms along the Norwegian coast. Here we analyse two years of test-data from biological assays designed to detect sensitivity-levels towards the pesticides azamethiphos and deltamethrin, both among the most common pesticides used in bath-treatments of farmed salmon in Norway in later years. The focus of the analysis is on how different variables predict the binomial outcome of the bioassay tests, being whether L. salmonis are immobilized/die or survive pesticide exposure. We found that local kernel densities of bath treatments, along with a spatial geographic index of test-farm locations, were significant predictors of the binomial outcome of the tests. Furthermore, the probability of L. salmonis being immobilized/dead after test-exposure was reduced by odds-ratios of 0.60 (95% CI: 0.42–0.86) for 2014 compared to 2013 and 0.39 (95% CI: 0.36–0.42) for low concentration compared to high concentration exposure. There were also significant but more marginal effects of parasite gender and developmental stage, and a relatively large random effect of test-farm. We conclude that the present data support an association between local intensities of bath treatments along the coast and the outcome of bioassay tests where salmon lice are exposed to azamethiphos or deltamethrin. Furthermore, there is a predictable structure of L. salmonis phenotypes along the coast in the data, characterized by high susceptibility to pesticides in the far north and far south, but low susceptibility in mid Norway. The study emphasizes the need to address local susceptibility to pesticides and the need for restrictive use of pesticides to preserve treatment efficacy.
Collapse
Affiliation(s)
- Peder A. Jansen
- Norwegian Veterinary Institute, Oslo, Norway
- Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
- * E-mail:
| | | | | | - Kari O. Helgesen
- NMBU School of Veterinary Science, Sea Lice Research Centre, Oslo, Norway
| | - Tor Einar Horsberg
- NMBU School of Veterinary Science, Sea Lice Research Centre, Oslo, Norway
| |
Collapse
|
36
|
Kaur K, Jansen PA, Aspehaug VT, Horsberg TE. Phe362Tyr in AChE: A Major Factor Responsible for Azamethiphos Resistance in Lepeophtheirus salmonis in Norway. PLoS One 2016; 11:e0149264. [PMID: 26882536 PMCID: PMC4755660 DOI: 10.1371/journal.pone.0149264] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 01/30/2016] [Indexed: 11/20/2022] Open
Abstract
Organophosphates (OP) are one of the major treatments used against the salmon louse (Lepeophtherius salmonis) in Norwegian salmonid aquaculture. The use of OP since the late 1970s has resulted in widespread resistant parasites. Recently, we reported a single mutation (Phe362Tyr) in acetylcholinesterase (AChE) as the major mechanism behind resistance in salmon louse towards OP. The present study was carried out to validate this mechanism at the field level. A total of 6658 salmon louse samples were enrolled from 56 different fish farms across the Norwegian coast, from Vest Agder in the south to Finnmark in the north. All the samples were genotyped using a TaqMan probe assay for the Phe362Tyr mutation. A strong association was observed between areas with frequent use of the OP (azamethiphos) and the Phe362Tyr mutation. This was confirmed at 15 sites where results from independently conducted bioassays and genotyping of parasites correlated well. Furthermore, genotyping of surviving and moribund parasites from six bioassay experiments demonstrated a highly significant negative correlation between the frequency of resistance alleles and the probability of dying when exposed to azamethiphos in a bioassay. Based on these observations, we could strongly conclude that the Phe362Tyr mutation is a major factor responsible for OP resistance in salmon louse on Norwegian fish farms.
Collapse
Affiliation(s)
- Kiranpreet Kaur
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033, Oslo, Norway
- * E-mail:
| | | | | | - Tor Einar Horsberg
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033, Oslo, Norway
| |
Collapse
|
37
|
Murray AG. Increased frequency and changed methods in the treatment of sea lice (Lepeophtheirus salmonis) in Scottish salmon farms 2005-2011. PEST MANAGEMENT SCIENCE 2016; 72:322-326. [PMID: 25712895 DOI: 10.1002/ps.3996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/03/2015] [Accepted: 02/18/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND The sea louse is the most economically and environmentally serious ectoparasite of marine salmonids. Sea lice have been largely controlled by treatment with a variety of medicines. In order to understand the sustainability of medicine usage, an analysis of sea louse treatment data has been carried out for all Scottish salmon farms from 2005 to 2011. RESULTS Overall, there was an increase from 0.156 to 0.282 treatments month(-1) ; treatments could involve one or multiple agents. This increase was mostly in bath treatments (cypermethrin in 2007, largely replaced by deltamethrin and azamethiphos in 2008). Treatments using in-feed treatments (emamectin benzoate and teflubenzuron) increased only slowly. Treatments involving more than one medicine in a single month also increased, as did the probability of follow-up treatments. Treatments were seasonal, with peaks of in-feed treatments in March and August and bath treatments more frequent between August and December. CONCLUSION Frequency of sea louse treatment increased substantially, with an increase in multiagent and follow-up treatments. This increase in treatment activity is expensive to the industry and increases exposure of the neighbouring environment. This indicates that earlier louse control practices were not sustainable and so adapted.
Collapse
|
38
|
Rose S, Altenburger R, Sturm A. Mixture toxicity effects of sea louse control agents in Daphnia magna. CHEMOSPHERE 2016; 144:599-606. [PMID: 26401637 DOI: 10.1016/j.chemosphere.2015.08.053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/11/2015] [Accepted: 08/14/2015] [Indexed: 06/05/2023]
Abstract
Caligid sea lice are ectoparasites causing major disease problems in industrial salmon farming. Sea louse control currently relies widely on parasiticides. Among non-target species, crustaceans are particularly susceptible to salmon delousing agents. Drug combinations have recently been suggested for sea louse control; however, no information is available on the non-target effects of such mixtures. To obtain first insights into combination effects of salmon parasiticides, acute toxicity tests with the crustacean model species Daphnia magna were conducted. Four compounds, including two organophosphates and two pyrethroids, were tested individually and in all pair-wise combinations at one fixed concentration ratio. For most combinations, observed toxicities were close to predictions assuming concentration additivity. However, deltamethrin and cypermethrin showed greater than predicted combination effects, while the inverse was observed for deltamethrin and malathion. The results demonstrate combination effects of anti-sea louse agents and suggest that predictions based on concentration additivity are in most cases protective.
Collapse
Affiliation(s)
- Stephanie Rose
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK
| | - Rolf Altenburger
- Department Bioanalytical Ecotoxicology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318, Leipzig, Germany
| | - Armin Sturm
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| |
Collapse
|
39
|
McEwan GF, Groner ML, Fast MD, Gettinby G, Revie CW. Using Agent-Based Modelling to Predict the Role of Wild Refugia in the Evolution of Resistance of Sea Lice to Chemotherapeutants. PLoS One 2015; 10:e0139128. [PMID: 26485023 PMCID: PMC4618729 DOI: 10.1371/journal.pone.0139128] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/08/2015] [Indexed: 11/18/2022] Open
Abstract
A major challenge for Atlantic salmon farming in the northern hemisphere is infestation by the sea louse parasite Lepeophtheirus salmonis. The most frequent method of controlling these sea louse infestations is through the use of chemical treatments. However, most major salmon farming areas have observed resistance to common chemotherapeutants. In terrestrial environments, many strategies employed to manage the evolution of resistance involve the use of refugia, where a portion of the population is left untreated to maintain susceptibility. While refugia have not been deliberately used in Atlantic salmon farming, wild salmon populations that migrate close to salmon farms may act as natural refugia. In this paper we describe an agent-based model that explores the influence of different sizes of wild salmon populations on resistance evolution in sea lice on a salmon farm. Using the model, we demonstrate that wild salmon populations can act as refugia that limit the evolution of resistance in the sea louse populations. Additionally, we demonstrate that an increase in the size of the population of wild salmon results in an increased effect in slowing the evolution of resistance. We explore the effect of a population fitness cost associated with resistance, finding that in some cases it substantially reduces the speed of evolution to chemical treatments.
Collapse
Affiliation(s)
- Gregor F. McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
- * E-mail:
| | - Maya L. Groner
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - Mark D. Fast
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - George Gettinby
- Department of Mathematics & Statistics, University of Strathclyde, Richmond Street, Glasgow, G1 1XH, Scotland, UK
| | - Crawford W. Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| |
Collapse
|
40
|
Marín SL, Ibarra R, Medina MH, Jansen PA. Sensitivity of Caligus rogercresseyi (Boxshall and Bravo 2000) to pyrethroids and azamethiphos measured using bioassay tests-A large scale spatial study. Prev Vet Med 2015; 122:33-41. [PMID: 26455388 DOI: 10.1016/j.prevetmed.2015.09.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 09/27/2015] [Accepted: 09/29/2015] [Indexed: 11/24/2022]
Abstract
The variety of antiparasitics that can be used against caligid copepods is limited and efforts are needed to maintain their efficacies. The objective of this study was to monitor the sensitivity of Caligus rogercresseyi, populations towards antiparasitics based on deltamethrin, cypermethrin and azamethiphos within and across geographic regions. The bioassay design consisted of exposing parasites collected from 23 farms to the different chemotherapeutants at the concentration and exposure times recommended for field treatment, under laboratory conditions, and evaluating the number of dead and live parasites 48h after exposure. Parasites were collected from 23 farms distributed in four macrozones in the Los Lagos region and three macrozones in the Aysén region. Parasite sensitivity was evaluated using a Generalized Linear Mixed Model of the Binomial family (Logit) fit by the maximum likelihood, using the lme4 package in R. Parasite gender, macrozone, and antiparasitics were used as fixed factors and farm was the random factor. The model including all the factors proved to be a useful tool for predicting parasite sensitivity. This approach identified (i) those macrozones with a greater likelihood of finding parasite populations which are more or less sensitive to the three antiparasitics, (ii) cases in which parasite sensitivity to the different antiparasitics varied within a given macrozone, (iii) differences in sensitivity between females and males and (iv) an important random effect associated with farm. The results indicate a spatial variability of parasite sensitivity to antiparasitics which, added to the continuous treatments applied on farms, suggest it is necessary to regularly update the sensitivity status in the macrozones. This would allow managers to improve their decision making processes regarding the type of antiparasitic to be used in a given situation. The one-concentration type bioassay performed in this study allowed us to perform a large spatial study with replicated tests of the sensitivity of C. rogercresseyi to pyrethroids and azamethiphos. Further studies should focus on the farm effects, the relationship between the sensitivity of parasites and field efficacy, as well as parasite population structure and connectivity with regard to parasite transmission between farms.
Collapse
Affiliation(s)
- S L Marín
- Instituto de Acuicultura, Universidad Austral de Chile, P.O. Box 1327, Puerto Montt, Chile.
| | - R Ibarra
- Instituto Tecnológico del Salmón, INTESAL de SalmonChile, Puerto Montt, Chile
| | - M H Medina
- Instituto Tecnológico del Salmón, INTESAL de SalmonChile, Puerto Montt, Chile
| | | |
Collapse
|
41
|
Identification and Molecular Characterization of Two Acetylcholinesterases from the Salmon Louse, Lepeophtheirus salmonis. PLoS One 2015; 10:e0125362. [PMID: 25938836 PMCID: PMC4418574 DOI: 10.1371/journal.pone.0125362] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/10/2015] [Indexed: 11/21/2022] Open
Abstract
Acetylcholinesterase (AChE) is an important enzyme in cholinergic synapses. Most arthropods have two genes (ace1 and ace2), but only one encodes the predominant synaptic AChE, the main target for organophosphates. Resistance towards organophosphates is widespread in the marine arthropod Lepeophtheirus salmonis. To understand this trait, it is essential to characterize the gene(s) coding for AChE(s). The full length cDNA sequences encoding two AChEs in L. salmonis were molecularly characterized in this study. The two ace genes were highly similar (83.5% similarity at protein level). Alignment to the L. salmonis genome revealed that both genes were located close to each other (separated by just 26.4 kbp on the L. salmonis genome), resulting from a recent gene duplication. Both proteins had all the typical features of functional AChE and clustered together with AChE-type 1 proteins in other species, an observation that has not been described in other arthropods. We therefore concluded the presence of two versions of ace1 gene in L. salmonis, named ace1a and ace1b. Ace1a was predominantly expressed in different developmental stages compared to ace1b and was possibly active in the cephalothorax, indicating that ace1a is more likely to play the major role in cholinergic synaptic transmission. The study is essential to understand the role of AChEs in resistance against organophosphates in L. salmonis.
Collapse
|
42
|
Kaur K, Helgesen KO, Bakke MJ, Horsberg TE. Mechanism behind Resistance against the Organophosphate Azamethiphos in Salmon Lice (Lepeophtheirus salmonis). PLoS One 2015; 10:e0124220. [PMID: 25893248 PMCID: PMC4403986 DOI: 10.1371/journal.pone.0124220] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 03/10/2015] [Indexed: 11/18/2022] Open
Abstract
Acetylcholinesterase (AChE) is the primary target for organophosphates (OP). Several mutations have been reported in AChE to be associated with the reduced sensitivity against OP in various arthropods. However, to the best of our knowledge, no such reports are available for Lepeophtheirus salmonis. Hence, in the present study, we aimed to determine the association of AChE(s) gene(s) with resistance against OP. We screened the AChE genes (L. salmonis ace1a and ace1b) in two salmon lice populations: one sensitive (n=5) and the other resistant (n=5) for azamethiphos, a commonly used OP in salmon farming. The screening led to the identification of a missense mutation Phe362Tyr in L. salmonis ace1a, (corresponding to Phe331 in Torpedo californica AChE) in all the samples of the resistant population. We confirmed the potential role of the mutation, with reduced sensitivity against azamethiphos in L. salmonis, by screening for Phe362Tyr in 2 sensitive and 5 resistant strains. The significantly higher frequency of the mutant allele (362Tyr) in the resistant strains clearly indicated the possible association of Phe362Tyr mutation in L. salmonis ace1a with resistance towards azamethiphos. The 3D modelling, short term survival experiments and enzymatic assays further supported the imperative role of Phe362Tyr in reduced sensitivity of L. salmonis for azamethiphos. Based on all these observations, the present study, for the first time, presents the mechanism of resistance in L. salmonis against azamethiphos. In addition, we developed a rapid diagnostic tool for the high throughput screening of Phe362Tyr mutation using High Resolution Melt analysis.
Collapse
Affiliation(s)
- Kiranpreet Kaur
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033 Oslo, Norway
- * E-mail:
| | - Kari Olli Helgesen
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033 Oslo, Norway
| | - Marit Jørgensen Bakke
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033 Oslo, Norway
| | - Tor Einar Horsberg
- NMBU School of Veterinary Science, Sea Lice Research Centre, PO Box 8146 Dep., NO-0033 Oslo, Norway
| |
Collapse
|
43
|
Molecular characterisation and functional analysis of LsChi2, a chitinase found in the salmon louse (Lepeophtheirus salmonis salmonis, Krøyer 1838). Exp Parasitol 2015; 151-152:39-48. [DOI: 10.1016/j.exppara.2015.01.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/22/2015] [Accepted: 01/26/2015] [Indexed: 12/18/2022]
|
44
|
Aaen SM, Helgesen KO, Bakke MJ, Kaur K, Horsberg TE. Drug resistance in sea lice: a threat to salmonid aquaculture. Trends Parasitol 2015; 31:72-81. [DOI: 10.1016/j.pt.2014.12.006] [Citation(s) in RCA: 271] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/04/2014] [Accepted: 12/15/2014] [Indexed: 01/22/2023]
|
45
|
Sutherland BJG, Poley JD, Igboeli OO, Jantzen JR, Fast MD, Koop BF, Jones SRM. Transcriptomic responses to emamectin benzoate in Pacific and Atlantic Canada salmon lice Lepeophtheirus salmonis with differing levels of drug resistance. Evol Appl 2014; 8:133-48. [PMID: 25685190 PMCID: PMC4319862 DOI: 10.1111/eva.12237] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/16/2014] [Indexed: 01/10/2023] Open
Abstract
Salmon lice Lepeophtheirus salmonis are an ecologically and economically important parasite of wild and farmed salmon. In Scotland, Norway, and Eastern Canada, L. salmonis have developed resistance to emamectin benzoate (EMB), one of the few parasiticides available for salmon lice. Drug resistance mechanisms can be complex, potentially differing among populations and involving multiple genes with additive effects (i.e., polygenic resistance). Indicators of resistance development may enable early detection and countermeasures to avoid the spread of resistance. Here, we collect sensitive Pacific L. salmonis and sensitive and resistant Atlantic L. salmonis from salmon farms, propagate in laboratory (F1), expose to EMB in bioassays, and evaluate either baseline (Atlantic only) or induced transcriptomic differences between populations. In all populations, induced responses were minor and a cellular stress response was not identified. Pacific lice did not upregulate any genes in response to EMB, but downregulated degradative enzymes and transport proteins at 50 ppb EMB. Baseline differences between sensitive and now resistant Atlantic lice were much greater than responses to exposures. All resistant lice overexpressed degradative enzymes, and resistant males, the most resistant group, overexpressed collagenases to the greatest extent. These results indicate an accumulation of baseline expression differences related to resistance.
Collapse
Affiliation(s)
- Ben J G Sutherland
- Centre for Biomedical Research, Department of Biology, University of Victoria Victoria, BC, Canada ; Institut de Biologie Intégrative et des Systèmes (IBIS), Département de biologie, Université Laval Québec, QC, Canada
| | - Jordan D Poley
- Hoplite Lab, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island Charlottetown, PEI, Canada
| | - Okechukwu O Igboeli
- Hoplite Lab, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island Charlottetown, PEI, Canada
| | - Johanna R Jantzen
- Centre for Biomedical Research, Department of Biology, University of Victoria Victoria, BC, Canada
| | - Mark D Fast
- Hoplite Lab, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island Charlottetown, PEI, Canada
| | - Ben F Koop
- Centre for Biomedical Research, Department of Biology, University of Victoria Victoria, BC, Canada
| | | |
Collapse
|
46
|
Besnier F, Kent M, Skern-Mauritzen R, Lien S, Malde K, Edvardsen RB, Taylor S, Ljungfeldt LER, Nilsen F, Glover KA. Human-induced evolution caught in action: SNP-array reveals rapid amphi-atlantic spread of pesticide resistance in the salmon ecotoparasite Lepeophtheirus salmonis. BMC Genomics 2014; 15:937. [PMID: 25344698 PMCID: PMC4223847 DOI: 10.1186/1471-2164-15-937] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 10/16/2014] [Indexed: 12/23/2022] Open
Abstract
Background The salmon louse, Lepeophtheirus salmonis, is an ectoparasite of salmonids that causes huge economic losses in salmon farming, and has also been causatively linked with declines of wild salmonid populations. Lice control on farms is reliant upon a few groups of pesticides that have all shown time-limited efficiency due to resistance development. However, to date, this example of human-induced evolution is poorly documented at the population level due to the lack of molecular tools. As such, important evolutionary and management questions, linked to the development and dispersal of pesticide resistance in this parasite, remain unanswered. Here, we introduce the first Single Nucleotide Polymorphism (SNP) array for the salmon louse, which includes 6000 markers, and present a population genomic scan using this array on 576 lice from twelve farms distributed across the North Atlantic. Results Our results support the hypothesis of a single panmictic population of lice in the Atlantic, and importantly, revealed very strong selective sweeps on linkage groups 1 and 5. These sweeps included candidate genes potentially connected to pesticide resistance. After genotyping a further 576 lice from 12 full sibling families, a genome-wide association analysis established a highly significant association between the major sweep on linkage group 5 and resistance to emamectin benzoate, the most widely used pesticide in salmonid aquaculture for more than a decade. Conclusions The analysis of conserved haplotypes across samples from the Atlantic strongly suggests that emamectin benzoate resistance developed at a single source, and rapidly spread across the Atlantic within the period 1999 when the chemical was first introduced, to 2010 when samples for the present study were obtained. These results provide unique insights into the development and spread of pesticide resistance in the marine environment, and identify a small genomic region strongly linked to emamectin benzoate resistance. Finally, these results have highly significant implications for the way pesticide resistance is considered and managed within the aquaculture industry. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-937) contains supplementary material, which is available to authorized users.
Collapse
|
47
|
Helgesen KO, Bravo S, Sevatdal S, Mendoza J, Horsberg TE. Deltamethrin resistance in the sea louse Caligus rogercresseyi (Boxhall and Bravo) in Chile: bioassay results and usage data for antiparasitic agents with references to Norwegian conditions. JOURNAL OF FISH DISEASES 2014; 37:877-890. [PMID: 24697556 DOI: 10.1111/jfd.12223] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/29/2013] [Accepted: 11/29/2013] [Indexed: 06/03/2023]
Abstract
The sea louse Caligus rogercresseyi is a major threat to Chilean salmonid farming. Pyrethroids have been used for anticaligus treatments since 2007, but have shown reduced effect, most likely due to resistance development. Pyrethroid resistance is also a known problem in Lepeophtheirus salmonis in the Northern Hemisphere. This study describes the development of deltamethrin resistance in C. rogercresseyi based on bioassays and usage data for pyrethroids in Chilean aquaculture. These results were compared to bioassays from L. salmonis from Norway and to Norwegian usage data. Available deltamethrin bioassay results from 2007 and 2008, as well as bioassays from Norway, were collected and remodelled. Bioassays were performed on field-collected sea lice in region X in Chile in 2012 and 2013. Bioassays from 2007 were performed prior to the introduction of pyrethroids to the Chilean market. Both the results from 2008 and 2012 showed an increased resistance. Increased pyrethroid resistance was also indicated by the increased use of pyrethroids in Chilean aquaculture compared with the production of salmonids. A similar trend was seen in the Norwegian usage data. The bioassay results from Chile from 2012 and 2013 also indicated a difference in the susceptibility to deltamethrin between male and female caligus.
Collapse
Affiliation(s)
- K O Helgesen
- Department of Pharmacology and Toxicology, Norwegian School of Veterinary Science, Oslo, Norway
| | | | | | | | | |
Collapse
|
48
|
Murray AG. A Modelling Framework for Assessing the Risk of Emerging Diseases Associated with the Use of Cleaner Fish to Control Parasitic Sea Lice on Salmon Farms. Transbound Emerg Dis 2014; 63:e270-7. [DOI: 10.1111/tbed.12273] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Indexed: 11/30/2022]
|
49
|
Núñez-Acuña G, Valenzuela-Muñoz V, Marambio JP, Wadsworth S, Gallardo-Escárate C. Insights into the olfactory system of the ectoparasite Caligus rogercresseyi: molecular characterization and gene transcription analysis of novel ionotropic receptors. Exp Parasitol 2014; 145:99-109. [PMID: 25131775 DOI: 10.1016/j.exppara.2014.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 06/13/2014] [Accepted: 08/03/2014] [Indexed: 01/09/2023]
Abstract
Although various elements of the olfactory system have been elucidated in insects, it remains practically unstudied in crustaceans at a molecular level. Among crustaceans, some species are classified as ectoparasites that impact the finfish aquaculture industry. Thus, there is an urgent need to identify and comprehend the signaling pathways used by these in host recognition. The present study, through RNA-seq and qPCR analyses, found novel transcripts involved in the olfactory system of Caligus rogercresseyi, in addition to the transcriptomic patterns expressed during different stages of salmon lice development. From a transcriptomic library generated by Illumina sequencing, contigs that annotated for ionotropic receptors and other genes implicated in the olfactory system were identified and extracted. Full length mRNA was obtained for the ionotropic glutamate receptor 25, which had 3923 bp, and for the glutamate receptor ionotropic kainate 2, which had 2737 bp. Furthermore, two other transcripts identified as glutamate receptor, ionotropic kainate 2-like were found. In silico analysis was performed for the transcription expression from different stages of development in C. rogercresseyi, and clusters according to RPKM values were constructed. Gene transcription data were validated through qPCR assays in ionotropic receptors, and showed an expression of glutamate receptor 25 associated with the copepodid stage whereas adults, especially male adults, were associated with the kainate 2 and kainate 2-like transcripts. Additionally, gene transcription analysis of the ionotropic receptors showed an overexpression in response to the presence of masking compounds and immunostimulant in salmon diets. This response correlated to a reduction in sea lice infection following in vivo challenge. Diets with masking compounds showed a decrease of lice infestation of up to 25%. This work contributes to the available knowledge on chemosensory systems in this ectoparasite, providing novel elements towards understanding the host-finding process of the salmon louse C. rogercresseyi.
Collapse
Affiliation(s)
- Gustavo Núñez-Acuña
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, P.O. Box 160-C, Concepción, Chile
| | - Valentina Valenzuela-Muñoz
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, P.O. Box 160-C, Concepción, Chile
| | | | | | - Cristian Gallardo-Escárate
- Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, P.O. Box 160-C, Concepción, Chile
| |
Collapse
|
50
|
Frenzl B, Migaud H, Fjelldal PG, Shinn AP, Taylor JF, Richards RH, Glover KA, Cockerill D, Bron JE. Triploid and diploid Atlantic salmon show similar susceptibility to infection with salmon lice Lepeophtheirus salmonis. PEST MANAGEMENT SCIENCE 2014; 70:982-988. [PMID: 23983154 DOI: 10.1002/ps.3639] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/29/2013] [Accepted: 08/23/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Sea lice infection is the most expensive disease factor for Atlantic salmon sea-cage farming. For triploid salmon to be accepted as a commercial possibility, investigation of susceptibility of triploid salmon to sea lice infection is a fundamental milestone. The susceptibility of diploid and triploid salmon to infection with Lepeophtheirus salmonis was examined in a tank trial in Scotland, a tank trial in Norway and a cage trial in Scotland. RESULTS Following a single infection challenge, results indicated a significant correlation between fish size and the number of attached sea lice. Triploid fish were larger than diploids at the smolt stage. In the tank trials, no difference was found between infection levels on diploids and triploids after a single infection challenge. The tank trial in Scotland continued with a second infection challenge of the same fish, which also showed no infection differences between ploidies. A borderline correlation between first infection and re-infection intensity was found for PIT-tagged diploid salmon examined after each challenge. No significant difference in louse infection between diploid and triploid salmon (∼2 kg) was found in the cage trial undertaken under commercial conditions. CONCLUSION This study concludes that triploid Atlantic salmon are not more susceptible to sea louse infection than diploid fish.
Collapse
Affiliation(s)
- Benedikt Frenzl
- Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK
| | | | | | | | | | | | | | | | | |
Collapse
|