Atlantic salmon infected with salmon lice are more susceptible to new lice infections

Ugelvik, Mathias Stølen; Mo, Tor Atle; Mennerat, Adèle; Skorping, Arne

doi:10.1111/jfd.12514

Cited by 11 publications

(20 citation statements)

References 36 publications

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“…It is somehow unclear at this stage what consequences such adaptive changes may have in epidemiological terms, and knowledge about the life history of salmon lice is still expanding (e.g., (Ugelvik, Mo, et al., ; Ugelvik, Skorping, et al., ). From earlier studies, it seems that faster life histories correlate with higher levels of virulence (Mennerat et al., ), which is consistent with virulence evolution theory and more specifically the existence of a virulence—transmission tradeoff (Alizon, Hurford, Mideo, & Van Baalen, ; Cressler, Mc, Rozins, Van den Hoogen, & Day, ).…”

Section: Discussionmentioning

confidence: 99%

“…Fecundity of wild and farmed salmon lice was compared using a linear mixed‐effect model ( lmer ) with status (farmed vs. wild) and reproductive event (from 1 to 5) as factors. Because parasite load varied across fish hosts and is known to negatively affect salmon lice fecundity (Ugelvik, Mo, Mennerat, & Skorping, ; Ugelvik, Skorping, et al., ), we also included the number of female lice on each fish as a covariate. Room (1 vs. 2) and Tank (nested within Room) were used as random effect factors.…”

Section: Methodsmentioning

confidence: 99%

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Invest more and die faster: The life history of a parasite on intensive farms

Mennerat

Ugelvik

Jensen

et al. 2017

Evolutionary Applications

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Invest more and die faster: The life history of a parasite on intensive farms

Mennerat

Ugelvik

Jensen

et al. 2017

Evolutionary Applications

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show abstract

“…Recent results indicate that mechanisms that increase aggregation could even be selected for in natural populations, where both host availability and lice intensities are low, because they would improve the mating opportunities of the lice (Ugelvik et al . ).…”

Section: Discussionmentioning

confidence: 97%

“…whereby the establishment of new parasites is made easier on already infected hosts) (Churcher, Filipe & Basanez ; Ugelvik et al . ).…”

Section: Introductionmentioning

confidence: 97%

Parasite fecundity decreases with increasing parasite load in the salmon louse Lepeophtheirus salmonis infecting Atlantic salmon Salmo salar

Ugelvik

Skorping

Mennerat

2016

Journal of Fish Diseases

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Aggregation is common amongst parasites, where a small number of hosts carry a large proportion of parasites. This could result in density-dependent effects on parasite fitness. In a laboratory study, we explored whether parasite load affected parasite fecundity and survival, using ectoparasitic salmon lice (Lepeophtheirus salmonis Krøyer, 1837) infecting Atlantic salmon (Salmo salar) hosts. We found a significant reduction in fecundity with higher parasite load, but no significant effect on survival. Together with previous findings, this suggests that stronger competition amongst female lice under high parasite load is a more likely explanation than increased host immune response.

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“…The pattern likely results from multiple factors including heterogeneity in (1) individual host exposure to infection (Murray ) and host susceptibility (Lysne and Skorping , Ugelvik et al. ), (2) sea louse choice of host, or (3) competition with other parasite species (Morand et al. , Bottomley et al.…”

Section: Discussionmentioning

confidence: 99%

Mate limitation in sea lice infesting wild salmon hosts: the influence of parasite sex ratio and aggregation

et al. 2017

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Mate limitation in dioecious parasite species has the potential to impact parasite population growth. Our focus of interest was the influence of parasite sex distribution among hosts on parasite reproduction and transmission dynamics for populations of ectoparasitic sea lice (Lepeophtheirus salmonis Krøyer) establishing on wild juvenile salmon hosts. The data included more than 139,000 out‐migrating juvenile pink salmon (Oncorhynchus gorbuscha (Walbaum)) and chum salmon (Oncorhynchus keta (Walbaum)) in British Columbia, Canada, sampled over nine years. For almost all years, the sex ratio of the reproductive stages of the sea lice was female‐biased. The probability of a female being able to mate (i.e., of being attached to a fish also carrying a male louse) increased with increasing parasite abundance and parasite aggregation. We compared, with expected modeling predictions, the observed prevalence of pairs of sea lice (i.e., one reproductive louse of each sex) on a given fish and the observed probability of a female being able to mate. These comparisons showed that male and female sea lice tend to be distributed together rather than separately on hosts. Distribution together means that sea lice are distributed randomly on hosts according to a common negative binomial distribution, whereas distribution separately means that males are distributed according to a negative binomial and females are distributed in their own negative binomial among hosts. Despite the tendency for distribution together we found that, in every year, at least 30% of reproductive female sea lice experience mate limitation. This Allee effect will result in submaximal rates of parasite reproduction at low parasite abundances and may limit parasite transmission. The work has important implications for salmon parasite management and the health both of captive farm salmon populations and migratory wild stocks. More broadly, these results demonstrate the potential impact of mate limitation as a constraint to the establishment and spread of wild ectoparasite populations.

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Atlantic salmon infected with salmon lice are more susceptible to new lice infections

Cited by 11 publications

References 36 publications

Invest more and die faster: The life history of a parasite on intensive farms

Invest more and die faster: The life history of a parasite on intensive farms

Parasite fecundity decreases with increasing parasite load in the salmon louse Lepeophtheirus salmonis infecting Atlantic salmon Salmo salar

Mate limitation in sea lice infesting wild salmon hosts: the influence of parasite sex ratio and aggregation

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