A Passive Haemagglutination Inhibition Assay for the Identification of Stomach Contents of Invertebrate Predators

Abstract

A passive hemagglutination inhibition (PHI) assay for the identification of stomach contents of invertebrate predators is described. When used in a system involving a wolf spider preying on 3 spp. of aquatic insects, PHI was up to 2 orders of magnitude more sensitive than the precipitin test while exhibiting between-genus specificity. The facilities needed for the performance of PHI assays are about as elaborate as those used in precipitin testing. The principal disadvantage of PHI is its requirement for a continual source of antigen, a requirement which should not, however, be difficult to satisfy where the prey are in culture or otherwise abundant. PHI was used to detect a wide variety of plant and animal materials, suggesting that it is generally applicable to studies of predator-prey interactions regardless of prey taxon.