Development of Monoclonal Antibodies to Pear Psylla (Hemiptera: Psyllidae) and Evaluation of Field Predation by Two Key Predators

Abstract

The pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), and related psyllids are important pests of pear (Pyrus spp.) worldwide. Many of these pests are thought to be partially controlled by predatory insects. To improve our understanding of the predator species that attack pear psylla, we developed monoclonal antibodies (MAbs) against this pest for predator gut content studies. Mice were immunized with homogenates of nymphal, adult, and egg stages of pear psylla. A mouse immunized with nymph homogenate showed high activity against all three antigen types and was used for MAb development. From 952 hybridomas screened, 35 showed good activity to pear psylla and low activity against nontarget arthropods. Four MAbs were retained: two from immunoglobulin M (IgM)-secreting hybridomas, both with high activity against all stages of psylla except young eggs, and two immunoglobin G-secreting hybridomas, both with high activity against psylla eggs and gravid adult females. Using one of the IgM-MAbs, pear psylla remains were detected in the predatory bugs Anthocoris tomentosus Pericart (Heteroptera: Anthocoridae) and Deraeocoris brevis (Uhler) (Heteroptera: Miridae) in laboratory feeding trials. Digestion half lives typically exceeded 24 h and were dependent on meal size and predator life stage. Gut content analysis of 970 field-collected D. brevis and Anthocoris spp. showed that the proportion which fed on psylla averaged 59% and that percentage closely tracked the density of pear psylla nymphs during three seasons. The utility of these antibodies for the study of trophic interactions and habitat management in relation to biological control of pear psylla is discussed.