The North American crayfish Procambarus clarkii and the biological control of schistosome-transmitting snails in Kenya: Laboratory and field investigations

Abstract

The Louisiana red swamp crayfish, Procambarus clarkii (Girard), was examined for its ability to serve as a biological control agent of Biomphalaria pfeifferi (Krauss), a molluscan intermediate host of human schistosomiasis in Kenya. Either two or four P. clarkii in large (100 × 60 × 60 cm) outdoor aquaria were able to significantly reduce B. pfeifferi abundance relative to control aquaria lacking crayfish, in experiments lasting 5, 15, or 30 days. B. pfeifferi was completely eliminated from aquaria containing four crayfish for 30 days. The ability of P. clarkii to alter the abundance of Nymphaea caerulea Savigny, a common aquatic plant with which B. pfeifferi is known to be positively associated, was also assessed. Crayfish were able to significantly reduce N. caerula abundance in both the above-described aquaria as well as in field enclosure cages (75 × 75 × 45 cm), but only when four crayfish were present for 30 days. Our results imply that P. clarkii may have potential both as a predator of and as a resource competitor with schistosome-transmitting snails in East Africa.