A false-positive food chain error associated with a generic predator gut content ELISA.

Conventional prey-specific gut content ELISA (enzyme-linked immunosorbent assay) and PCR (polymerase chain reaction) assays are useful for identifying predators of insect pests in nature. However, these assays are prone to yielding certain types of food chain errors. For instance, it is possible that prey remains can pass through the food chain as the result of a secondary predator (hyperpredator) consuming a primary predator that had previously consumed the pest. If so, the pest-specific assay will falsely identify the secondary predator as the organism providing the biological control services to the ecosystem. Recently, a generic gut content ELISA was designed to detect protein-marked prey remains. That assay proved to be less costly, more versatile, and more reliable at detecting primary predation events than a prey-specific PCR assay. This study examines the chances of obtaining a 'false positive' food chain error with the generic ELISA. Data revealed that the ELISA was 100% accurate at detecting protein-marked Lygus hesperus Knight ( Hemiptera: Miridae) remains in the guts of two (true) primary predators, Hippodamia convergens Guérin- Méneville ( Coleoptera: Coccinellidae) and Collops vittatus ( Say) ( Coleoptera: Melyridae). However, there was also a high frequency (70%) false positives associated with hyperpredators, Zelus renardii Kolenati ( Hemiptera: Reduviidae), that consumed a primary predator that possessed protein-marked L. hesperus in its gut. These findings serve to alert researchers that the generic ELISA, like the PCR assay, is susceptible to food chain errors. [ABSTRACT FROM AUTHOR]