Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis

Abstract

The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis–a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations.

First evidence of a causal link between genetic variation and thermal adaptation in a schistosome host snail

“…Furthermore, local adaptation could also manifest in response to predator cues (Dalesman et al, 2015; Goeppner et al, 2020). This implies that biological control measures reliant on the introduction of snail predators, such as fish (Arostegui et al, 2019), waterbugs (Younes et al, 2017), or prawns (Faiad et al, 2023; Monde et al, 2017; Swartz et al, 2015), may exhibit reduced efficacy in areas where natural predators are already present.…”

Procambarus virginalis Lyko, 2017: A new threat to Iberian inland waters

“…Few data are known on the impact of this species on the native fauna and the ecosystems it manages to colonise. There are only experimental data on its predation on gastropod molluscs of the families Planorbidae ( Biomphalaria glabrata ) and Bulimidae ( Bulimus truncatus ) (Faiad et al., 2023 ). Although neither of these species is native to the habitat where P. virginalis is herein reported, there are other indigenous species of planorbids (e.g.…”

“…Few data are known on the impact of this species on the native fauna and the ecosystems it manages to colonise. There are only experimental data on its predation on gastropod molluscs of the families Planorbidae (Biomphalaria glabrata) and Bulimidae (Bulimus truncatus) (Faiad et al, 2023).…”