Laboratory screening of nematodes isolated from South Australia for potential as biocontrol agents of helicid snails

The helicid snails Cernuella virgata, Theba pisana, Cochlicella acuta, and Cochlicella barbara are introduced pests in grain crops and pastures in sou thern Australia. A survey for nematodes with potential for biocontrol of th ese snails was carried out and six local nematode isolates were tested for their ability to kill C. virgata, T. pisana, and C. acuta using a soil-base d laboratory bioassay. The rhabditid isolate R 954 was highly pathogenic to all three snail species with mortality increasing with increasing nematode densities and exposure time. C. acuta was most susceptible to R 954. In ad dition, high mortalities followed exposure of C. acuta to two cephalobid is olates, C 916 and C 920. Snail mortality caused by the other nematode isola tes tested was too low for further consideration as possible biocontrol age nts. (C) 1999 Academic Press.