GENE FLOW IN THE EXOTIC 14-SPOTTED LADYBIRD BEETLE, PROPYLEA-QUATUORDECIMPUNCTATA

Propylea quatuordecimpunctata is a Palearctic ladybird beetle that has recently become established fortuitously in northeastern North Americ a. This predator has also been cultured by the United States Departmen t of Agriculture from geographically diverse Old World populations and propagated for release in the U.S.A. Massive releases of P. quatuorde cimpunctata have not resulted in any recognized established population s, raising a number of questions about its population genetics. We sam pled beetles for electrophoretic variation in three feral populations in the U.S.A., one feral population in Europe, one cultured population from Canada, and six cultured populations from the Old World. Of the 31 putative genetic loci resolved, 26 were polymorphic (84%). Mean het erozygosity was 18.32 +/- 2.84% among all loci and was 21.84 +/- 2.89% among only polymorphic loci. Cultured and feral populations showed si milar levels of heterozygosity at the 11 loci scored. New World and Ol d World beetles showed no significant differences in heterozygosities. Wright's fixation index F-ST was 0.034 +/- 0.021 among feral populati ons and 0.331 +/- 0.101 among cultured populations. Drift was the majo r force driving differentiation of cultured beetle populations. Our da ta do not suggest that the failure of P. quatuordecimpunctata to becom e established in areas where it was deliberately released was related to a paucity of genic diversity.