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ARS Home » Research » Publications at this Location » Publication #113082
Title: IDENTIFYING KEY CEREAL APHID PREDATORS MY MOLECULAR GUT ANALYSIS

Author
item CHEN, YI - OKLAHOMA STATE UNIVERSITY
item GILES, KRISTOPHER - OKLAHOMA STATE UNIVERSITY
item PAYTON, M - OKLAHOMA STATE UNIVERSITY
item Greenstone, Matthew

Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2000
Publication Date: 1/1/2001
Citation: N/A

Interpretive Summary: The incorporation of biological control into integrated pest management programs for wheat and barley insect pests is hampered by a lack of information on the role of insect and other arthropod predators. In a process analogous to DNA fingerprinting used in forensic cases, we have developed polymerase chain reaction primers to detect the remains of aphid pests in the guts of predators. These tools will enable us to determine which are the most important predators of aphids, and use the information to develop aphid management programs that improve the effectiveness of those predators.

Technical Abstract: We describe polymerase chain reaction (PCR) primers and assays for gut analysis of aphid predators. The primers were designed to amplify aphid mitochondrial COII fragments ranging in size from approximately 75 to 400 bp. Using them, we are able to amplify and distinguish six species of U.S. Great Plains cereal aphids, including two congeners, Rhopalosiphum maidis (Fitch) and R. padi (L.), and to detect them in extracts of coccinellid an chrysopid predators. We devised a protocol for deriving half-lives of detectability for the DNA of a single aphid by predators maintained under realistic dietary and temperature conditions. Using this protocol and PCR primers for a 198 bp fragment, we determined statistically different half- lives of detectability for a single R. maidis of 3.95 h in Chrysopa plorabunda (Fitch) and 8.78 h in Hippodamia convergens Guerin. The detectability half-life for a 339 bp R. maidis fragment was statistically longer in C. plorabunda, suggesting that primers for detection of COII fragments in predator extracts should be no longer than about 250 bp. The sensitivity of the assay is 10X-7 aphid equivalent. For species-specific predator gut analysis, PCR is superior to monoclonal antibody (MAb) technology, giving comparable detectability half-lives with lower expense, shorter development times, and greater certainty of a successful outcome. The only superior attribute of MAb technology, the ability to provide stage or instar level specificity, could be achieved by reverse transcriptase PCR.