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 distri bution of genetic diversity in Aphthona nigriscutis Foudras populations 5 t o 9 yrs following their introduction to sites in North and South Dakota for the purpose of biologically controlling leafy spurge, Euphorbia esula L. G ene expression patterns of two enzymes, phosphoglucomutase, (PGM) and malat e 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 simila r to each other genetically than they were to the Hungarian population. Nor th American populations were also genetically differentiated from each othe r as well as the Hungarian population according to geography and environmen t. 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 selectio n would, however, enhance the species' adaptability to geographic regions o f the Dakotas as it served to distant populations genetically.