A Monoclonal Antibody to the Shield Beetle Cassida rubiginosa (Coleoptera, Chrysomelidae): A Tool for Predator Gut Analysis

We describe the development of a monoclonal antibody (MAb) to the hemolymph of fifth-instar larvae of the shield beetle, Cassida rubiginosa Muell. (Coleoptera, Chrysomelidae), to be used as a tool for predator gut analysis. The MAb reacts with all life stages of C. rubiginosa, shows no cross-reactions outside the genus Cassida (31 herbivorous insect species and 12 potential predators of C. rubiginosa were tested), and is less reactive with other Cassida species than with C. rubiginosa. Specificity tests were conducted using an indirect enzyme-linked immunosorbent assay. Western blot analysis following SDS–PAGE showed that the MAb reacts with a single protein of molecular weight 32 kDa. The immunoblot of a native PAGE showed a reaction with three bands, the monomer of 32 kDa and two bands with approximate molecular weights of 60 and 90 kDa. Using this MAb, we were able to unambiguously identify individuals of the model predator Nabis mirmicoides Costa (Hemiptera, Nabidae) after feeding on one C. rubiginosa last-instar larva. The MAb may be useful for predator gut analysis to identify the predator complex of C. rubiginosa.