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Title: INTRASPECIFIC MITOCHONDRIAL DNA VARIATION IN THE COLORADO POTATO BEETLE, LEPTINOTARSA DECEMLINETA (COLEOPTERA: CHRYSOMELIDAE)

Author
item AZERADO-ESPIN, A - UMICHMP BRAZIL
item Schroder, Robert
item RODERICK, G - UNIV HAWAII
item Sheppard, Walter

Submitted to: Biochemical Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Colorado Potato Beetle (CPB) is one of the most destructive pests of potatoes in the U.S. Previous research on CPB allozymes, karyotypes and mtDNA had reported little genetic variation existed in U.S. populations and was unable to correlate existing distributions with presumed historical origins for CPB. We report mtDNA variation in CPB that can be used to determine population structure for this important pest. Our findings indicate that populations from Texas, on native Solanum hosts, contain extensive genetic variability, including most of the genetic variants found among the other populations on potatoes. In contracts, CPB collected from potato fields in WA, OH and MD often contained high frequencies of unique genetic markers, indicating that these populations may have started from small founding populations and do not presently exhibit extensive gene flow. These data will be useful for researchers studying the evolution of host shifts, the potential for colonization and gene movement and the spread of insecticide resistance in this species.

Technical Abstract: Restriction endonuclease analyses of mitochondrial DNA (mtDNA) were used to examine the genetic variability and population structure in Leptinotarsa decemlineata (Say). A group of three enzymes, EcoRI, HpaI and PstI, was used to reveal polymorphism both within and among some of the ten populations tested, yielding 16 haplotypes in combination. The frequencies of these 16 haplotypes differed significantly across geographic regions, indicating some partitioning of mtDNA haplotypes. Estimates of mtDNA sequence divergence (delta) between haplotypes ranged from 0.016 to 0.135%, suggesting local differentiation of mtDNA in some populations. Analysis of these data suggests that Texas was colonized by more than one mtDNA lineage, most likely originating in Mexico. We hypothesize that a larger founder size for the initial introductions or high levels of variability in the parent population at the edge of the CPB expanding range led to the initial partitioning of haplotypes observed in samples from Texas.