A Monoclonal Antibody for the Detection of Arionid Slug Remains in Carabid Predators

Conventional enzyme-linked immunosorbent assay systems (ELISA), using polyclonal antisera, cannot be applied in fully quantitative investigations of predator-prey interactions in biological control studies, where a number of related prey genera are present that react, to different degrees, with the chosen antisera. The greater specificity achievable with monoclonal antibodies can surmount this difficulty. This paper reports the development of a monoclonal antibody, to Arion ater (L.) hemocyanin, that can clearly identify arionid slugs from other pest genera, such as Deroceras and Milax sp., that are found in field crops. Having identified the prey in this manner, the gut contents of carabid beetles, and other predators, can be quantitatively assessed using monoclonal antibodies or polyclonal antisera raised to the appropriate prey genus, thus maximizing sensitivity and antigen detection periods. There were no significant cross-reactions between the monoclonal antibody and 19 nonmollusc alternative prey species, nor with predator proteins. The ELISA system employed was capable of detecting as little as 3.43 ng of hemocyanin. The monoclonal antibody recognized the remains of Arion hortensis Férussac tested following overnight consumption by Abax parallelepipedus Piller & Mitterpacher, but not after a further 24-h starvation period. The important possibility of using the monoclonal and polyclonal systems in combination, to determine the time since feeding, and hence to calculate the size of the original meal, was discussed.