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An immunological approach to distinguish arthropod viviphagy from necrophagy

Zilnik, Gabriel, Hagler, James R.
Biocontrol 2013 v.58 pp. 807-0
Bemisia tabaci, Chrysoperla rufilabris, Collops vittatus, Hippodamia convergens, arthropods, biological control agents, chickens, dead animals, digestive system, enzyme-linked immunosorbent assay, immunoglobulin G, necrophagy, predation, predators, rabbits
Scavenging activity of predators inhabiting agroecosystems has not been thorough investigated. Understanding the prevalence of necrophagy in predators is paramount to determining the effectiveness of biological control agents. A molecular predator gut content assay is described that can differentiate necrophagy from vivaphagy. Cadaver sweetpotato whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) and green lacewing, Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) serving as targeted prey items were marked with rabbit immunoglobulin G (IgG) protein and live prey items were marked with chicken IgG, respectively. The marked prey items were fed to convergent lady beetles, Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinellidae) and soft-winged flower beetles, Collops vittatus (Say) (Coleoptera: Melyridae). The frequency of detection of the protein-marked prey items in the gut of the predaceous beetles was assessed at 0, 3, 6, 12, 24 and 48 h after feeding using a rabbit-IgG-specific or chicken IgG-specific enzyme-linked immunosorbent assay (ELISA). Each IgG-specific ELISA detected the presence of the marker proteins in the gut of 90% of the predators up to 12 h after prey consumption. A laboratory feeding study was also conducted to determine the propensity that each predator species engages in vivaphagy and necrophagy. The laboratory feeding observations revealed that C. vittatus prefer carrion prey items. Finally, the laboratory observations of necrophagy were confirmed in a field study where C. vittatus was observed, directly and indirectly, feeding on H. convergens carcasses. The methodologies described here are useful for future studies on various aspects of insect predation.