Immunological approaches to the detection of predation upon New Zealand Flatworms (Tricladida: Terricola): Problems caused by shared epitopes with slugs (Mollusca: Pulmonata)

Abstract

Abstract The geographical distribution and rate of spread of the earthworm predator Artioposthia triangulata (Dendy), a planarian flatworm accidentally introduced to Britain from New Zealand, is thought to be influenced primarily by ecoclimatic factors. However, anomalies in the expected distribution pattern and population dynamics may be caused in part by predation, and therefore the possibility of using antibodies to detect flatworm remains amongst the gut contents of potential predators was investigated. Cross‐reactivity between an anti‐flatworm polyclonal antiserum and slugs was effectively eliminated by absorption against slug proteins. Similar cross‐reactivity between certain anti‐slug monoclonal antibodies, and flatworms, was also found, indicating similar protein sequences or epitopes. The possibility that these reactions were caused by an immunoglobulin‐binding protein within the flatworms, or endogenous peroxidases affecting ELISA results, was eliminated. Possible evolutionary explanations for such cross‐reactivity are discussed. These results strongly support the need to use fully characterized flatworm‐specific monoclonal antibodies for predation studies in the field, to quantify the role of predation in flatworm population dynamics and to identify potentially useful biological control agents.