Genetic Variation in Aphthona nigriscutis Foudras (Coleoptera: Chrysomelidae) Populations Introduced into the United States to Biologically Control Leafy Spurge

Cellulose acetate electrophoresis was used to examine the levels and distribution of genetic diversity in Aphthona nigriscutis Foudras populations 5 to 9 yrs following their introduction to sites in North and South Dakota for the purpose of biologically controlling leafy spurge, Euphorbia esula L. Gene expression patterns of two enzymes, phosphoglucomutase (PGM) and malate dehydrogenase (MDH), were analyzed to determine the genetic variation and distance among and between populations in North America and Hungary where the species is indigenous. Dakota populations were variable and more similar to each other genetically than they were to the Hungarian population. North American populations were also genetically differentiated from each other as well as the Hungarian population according to geography and environment. Gene flow probably did not account for this genetic variability because natural dispersal of A. nigriscutis was limited and large distances existed between A. nigriscutis sites. Novel mutations nurtured by natural selection would, however, enhance the species' adaptability to geographic regions of the Dakotas as it served to distant populations genetically.