ARS | Publication request: GENETIC DEMARCATION OF NORTHERN CORN ROOTWORM POPULATIONS REVEALED BY DNA MARKERS

Submitted to: National Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 13, 1999
Publication Date: N/A

Technical Abstract: The genetic variation of local and dispersed geographical populations of northern corn rootworms (NCR)(Diabrotica barberi), has been examined using mitochondrial DNA and nuclear ribosomal intergenic transcribed spacer (ITS1). NCR were collected at various sites across the corn belt (KS, NE, SD, IA, WI, IL, IN, OH). Long-PCR was used to amplify DNA segments comprising about 75%of the mtDNA. The mtDNA amplicons were screened for restriction fragment polymorphisms. Approximately 70 restriction fragments per individual have contributed to the RFLP comparisons and numerous mtDNA haplotypes have been identified. Polymorphism has been observed both within populations and between collection sites. A phylogeographic pattern of genetic diversity appears to be emerging with a genetic demarcation zone in east central Illinois. Distinct differences in haplotype frequencies occur on either side of the boundary. The nuclear rDNA ITS1 region has been examined for many of the same individuals. DNA sequence of a 644-646 bp amplicon from several individuals revealed four polymorphic sites. PCR-RFLP analysis with the restriction enzyme Bcl I on many of the same individuals used for mtDNA, detected two haplotypes. Many beetles had both BclI haplotypes present, which is indicative of heterogeneity. The eastern Illinois populations were fixed for haplotype "B", while South Dakota, Nebraska, and Kansas populations were predominately haplotype "A" or "A/B". Both mtDNA and ITS1 support an historic genetic boundary in Illinois.