May atyid shrimps act as potential vectors of crayfish plague?

Agata Mrugała,Miloš Buřič,Adam Petrusek,Antonín Kouba

doi:10.3897/neobiota.51.37718

Abstract

The causative agent of crayfish plague, Aphanomyces astaci Schikora, was long considered to be a specialist pathogen whose host range is limited to freshwater crayfish. Recent studies, however, provided evidence that this parasite does not only grow within the tissues of freshwater-inhabiting crabs but can also be successfully transmitted by them to European crayfish species. The potential to act as alternative A. astaci hosts was also indicated for freshwater shrimps. We experimentally tested resistance of two freshwater atyid shrimps: Atyopsis moluccensis (De Haan, 1849) and Atya gabonensis Giebel, 1875. They were infected with the A. astaci strain associated with the globally widespread North American red swamp crayfish, Procambarus clarkii (Girard, 1852), the typical host of the A. astaci genotype group D. As popular ornamental species, both shrimps may get in contact with infected P. clarkii not only in the wild but also in the aquarium trade. We assessed the potential of shrimps to transmit A. astaci to susceptible crayfish by cohabiting A. gabonensis previously exposed to A. astaci zoospores with the European noble crayfish, Astacus astacus (Linnaeus, 1758). In both experiments, the presence of A. astaci infection was analysed with species-specific quantitative PCR. We detected A. astaci in bodies and exuviae of both shrimp species exposed to A. astaci zoospores, however, the intensity of infection differed between the species and analysed samples; it was higher in A. moluccensis and the exuviae of both species. A. astaci was also detected in one A. astacus individual in the transmission experiment. This finding reveals that freshwater shrimps may be able to transmit A. astaci to crayfish hosts; this is particularly important as even a single successful infection contributes to the spread of the disease. Moreover, our results indicate that the tested shrimp species may be capable of resisting A. astaci infection and reducing its intensity through moulting. Although their potential to act as prominent A. astaci vectors requires further research, it should not be ignored as these freshwater animals may then facilitate A. astaci spread to susceptible crayfish species in aquarium and aquaculture facilities as well as in the wild.

Highlights

Invasive alien species (IAS) are considered one of the major threats to native biodiversity (Sala et al 2000), due to their wide range of negative impacts on the functioning of whole ecosystems and their communities (Blackburn et al 2014)
All C. destructor and A. gabonensis used in the control groups survived, whereas eight out of ten control A. moluccensis died before the end of the experimental trial
It is unlikely that freshwater-inhabiting crabs and shrimps are well-equipped against A. astaci; ; both groups seem resistant to the crayfish plague pathogen

Summary

Introduction

Invasive alien species (IAS) are considered one of the major threats to native biodiversity (Sala et al 2000), due to their wide range of negative impacts on the functioning of whole ecosystems and their communities (Blackburn et al 2014). The IAS may be responsible for an introduction of novel disease agents and facilitate the spread of the ones that already occur in their new ranges (Peeler et al 2011; Strauss et al 2012). The emergence in Europe of the oomycete Aphanomyces astaci Schikora, the causative agent of crayfish plague, exemplifies the devastating impacts that a novel pathogen may impose on native fauna. Its spread across the continent caused irreversible declines of native European crayfish populations and still threatens their remaining stocks (Alderman 1996; Holdich et al 2009), leading to its inclusion among the worst IAS in Europe (Vilà et al 2010) as well as worldwide (Lowe et al 2004)

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