Development of a Monoclonal Antibody for the Detection and Quantification of Predation on Slugs within the Arion hortensis agg. (Mollusca: Pulmonata)

The Arion hortensis agg. (Mollusca: Pulmonata) are major slug pests of agriculture and horticulture throughout much of the temperate World. A monoclonal antibody was created that could specifically identify and quantify the remains of these slugs within the carabid predator Pterostichus melanarius Illiger, a polyphagous species found in arable crops in Europe and North America. The antibody was shown to be specific for the two species of pest slug within this species aggregate, Arion distinctus Mabille and A. hortensis Férussac, and did not cross-react with any other invertebrates tested, including other slugs in the same genus. It proved to be highly sensitive in an enzyme-linked immunosorbent assay. The mean detection period for the remains of A. distinctus in predator foregut samples was 3.28 days at 16°C. However, A. distinctus remains could be identified in male carabids for 30% longer than in females, emphasizing the importance of separate analyses. The value of the antigen half-life as a measure of the detection period was questioned because analysis of covariance showed that the regression slopes for antigen decay were not significantly different between the two sexes, giving very similar half-lives (approx 18.5 h for females and 19 h for males). Calculated quantities of soluble slug proteins in predator foreguts declined more rapidly over time than concentrations, allowing separate assessment of the importance of these two variables on detection periods. It was concluded that a valuable new antibody had been created and characterized, which can be used for the analysis of predation in the field.