Predation preference of the crayfish Procambarus clarkii on schistosomiasis vector snails: influence of snail species, infection status, and size

Background Schistosomiasis control relies largely on preventive chemotherapy; however, rapid reinfection persists in many endemic settings due to continued transmission by freshwater snail intermediate hosts. Biological control using natural predators has been proposed as a complementary strategy to reduce vector snail populations. The invasive North American crayfish Procambarus clarkii , which preys on schistosome-transmitting snails, represents a promising candidate. However, the ecological and biological factors influencing predator–prey interactions between crayfish and vector snails remain poorly understood. Methods We evaluated the predatory potential of Procambarus clarkii on schistosomiasis vector snails under controlled laboratory conditions. Aquarium-based experiments examined predator–prey interactions involving crayfish and snail hosts ( Biomphalaria and Bulinus spp.). Experiments assessed the effects of snail species, infection status, prey size, and crayfish developmental stage (juvenile and adult) on predation dynamics. Predation outcomes were assessed using cumulative predation and time-to-depletion analyses. Results In early-time cumulative predation analysis, infected snails were consumed more frequently than uninfected snails (64.3% vs. 35.7%; exact binomial test, p  = 0.044). Time-to-depletion analysis also showed earlier clearance of infected snails (median 18 h vs. 20 h; paired Wilcoxon signed-rank test, p  = 0.002). In species comparison experiments, Biomphalaria snails were depleted more rapidly than Bulinus , with complete consumption of Biomphalaria (5/5 snails) observed in all replicate tanks within 48 h. Size-dependent assays showed that adult P. clarkii consumed larger snails more frequently than smaller snails. In predator–prey stage experiments, adult crayfish consumed similar proportions of adult and juvenile snails (82.8% vs. 80.6%), whereas juvenile crayfish consumed significantly more juvenile than adult snails (63/180 vs. 10/180; p  < 0.001). Conclusion Predation by Procambarus clarkii on schistosomiasis vector snails is influenced by snail infection status, species identity, prey size, and predator developmental stage. These findings provide experimental evidence supporting the potential role of crayfish as a complementary biological control agent within integrated schistosomiasis control strategies.