Standardization of prey immunomarking: Does a positive test always indicate predation?

Authors: Hagler, James; Casey, Miles; MANSFIELD, SARAH - Agresearch

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2018
Publication Date: 11/18/2018
Citation: Hagler, J.R., Casey, S.R., Mansfield, S. 2018. Standardization of prey immunomarking: Does a positive test always indicate predation? Biocontrol. 63:773-784. https://doi.org/10.1007/s10526-018-9905-5.
DOI: https://doi.org/10.1007/s10526-018-9905-5

Interpretive Summary: Knowledge of arthropod predation is an important component of a successful integrated pest management program. The most popular indirect method to assess predation is by examination of a predator’s stomach contents for the presence of pest-specific DNA. Unfortunately, this method is time consuming, costly, tedious, and has many limitations. An ARS scientist at Maricopa, AZ developed an immunological assay that can detect a unique protein biomarker applied to any targeted pest species. In turn, the biomarker is readily transferred to a predator during feeding. Studies were conducted to validate the effectiveness of the immunomarking assay method. Data revealed that the technique is very effective at detecting protein-marked prey remains in the guts of all types of predators. The study also revealed that, when possible, the protein marks should be applied internally to the prey to maximize the likelihood of detecting prey remains while minimizing the risk of obtaining false positive assay errors. The assay is far less expensive, time consuming, and tedious than the conventional DNA assay method. Refinement of this gut assay procedure provides researchers with a reliable alternative technique for evaluating prey choice of predators in agroecosystems.

Technical Abstract: A prey immunomarking procedure (PIP) in combination with generic anti-rabbit and anti-chicken immunoglobulin G (IgG) enzyme-linked immunosorbent assays (ELISA) are used frequently to study arthropod predation. This study was conducted to: i) further standardize the PIP as a tool for predator gut analysis research, ii) investigate the most effective means for administering IgG marks to prey items, and iii) assess the possibility of the PIP yielding false positive reactions as a consequence of a predator obtaining a mark by incidental contact with, or by a failed predation attempt on, a protein-marked prey item. The cosmopolitan pest, Lygus hesperus Knight (Hemiptera: Miridae) was tagged with either an external rabbit IgG mark, an internal chicken IgG mark, or a double (external rabbit IgG and internal chicken IgG) mark treatment. Then, the variously marked prey items were fed to chewing and piercing-sucking type predators and their gut contents were examined for the presence of IgG remains. Data revealed that all three marking treatments were highly effective at tagging targeted prey. However, ELISA results showed that the prey items should only be marked internally to maximize the likelihood of detecting prey remains while minimizing the risk of obtaining false positive errors. The merits and limitations of using the generic PIP for predator gut analysis research are discussed.