Temporal dynamics of spore release of the crayfish plague pathogen from its natural host, American spiny-cheek crayfish (Orconectes limosus), evaluated by transmission experiments

Abstract

The crayfish plague pathogen, Aphanomyces astaci, is one of the most serious threats to indigenous European crayfish species. The North American invasive spiny-cheek crayfish, Orconectes limosus, is an important source of this pathogen in central and western Europe. We evaluated potential changes in A. astaci spore release rate from infected individuals of this species by experiments investigating the pathogen transmission to susceptible noble crayfish, Astacus astacus. We filtered defined volumes of water regularly to quantify spore concentration, and sampled crayfish tissues at the end of the experiment. The filters and tissues were then tested for the presence of A. astaci DNA by species-specific quantitative PCR. Additionally, we tested the efficiency of horizontal transmission to apparently uninfected O. limosus. The experiments confirmed that A. astaci can be transmitted to susceptible crayfish during intermoult periods, and that the pathogen was more frequently detected in noble crayfish recipients than in American ones. The pathogen spore concentrations substantially varied in time, and significantly increased during moulting of infected hosts. Our study strengthens the evidence that although the likelihood of crayfish plague transmission by water transfer from localities with infected American crayfish might increase when these are moulting or dying, no time-periods can be proclaimed safe.

Niche modelling to guide conservation actions in France for the endangered crayfish Austropotamobius pallipes in relation to the invasive Pacifastacus leniusculus

“…Our projections might also underestimate the effect of human activities on crayfish distribution because our projections did not account for scenarios of potential land use changes (Préau et al, 2018;Titeux et al, 2016). Adding information on the presence of crayfish plague, which is carried by P. leniusculus (Filipova et al, 2013;Grandjean et al, 2017) and by other exotic crayfish as well (Gherardi, 2006;Svoboda et al, 2013), would also allow an improved recommendation of suitable locations for the conservation of A. pallipes.…”

Detection of crayfish plague spores in large freshwater systems

“…; Svoboda et al . ), and this increase should be notable when synchronized moulting occur (Pratten ). Further, there are several reports where signal crayfish have suffered from acute crayfish plague (Edgerton et al .…”

“…; Svoboda et al . ), while tissue analyses of the recently moulted crayfish would yield negative or low A. astaci PFU values. This emphasizes both that prevalence measures should take seasonal variation into account and that spore concentration cannot be assumed on the basis of prevalence measures from a single sampling event.…”

“…; Svoboda et al . ) revealed that A. astaci spores are frequently released from infected carrier NICS, with increased spore release in concurrence with moulting events and death. Even at low temperatures (4 °C), A. astaci spores were frequently released from the carriers (Strand et al .…”

Experimental evaluation of the potential for crayfish plague transmission through the digestive system of warm‐blooded predators

“…No A. astaci DNA was detected by filtration of water from the tanks with crayfish exposed to the predator excrements (the detection limit being ca 14 spores per litre), although the same method was successfully used to detect A. astaci in water tanks with infected North American crayfish (Svoboda et al, ). It is thus clear that no massive sporulation occurred in the experimental tanks at or shortly before the time of filtration (24 and 48 hr after the excrement addition).…”