Invasion genetics of A merican cherry fruit fly in E urope and signals of hybridization with the E uropean cherry fruit fly

The A merican cherry fruit fly is an invasive pest species in E urope, of serious concern in tart cherry production as well as for the potential to hybridize with the E uropean cherry fruit fly, R hagoletis cerasi L . ( D iptera: T ephritidae), which might induce new pest dynamics. In the first E uropean reports, the question arose whether only the eastern A merican cherry fruit fly, R hagoletis cingulata ( L oew) ( D iptera: T ephritidae), is present, or also the closely related western A merican cherry fruit fly, R hagoletis indifferens C urran. In this study, we investigate the species status of E uropean populations by comparing these with populations of both A merican species from their native ranges, the invasion dynamics in G erman (first report in 1993) and H ungarian (first report in 2006) populations, and we test for signals of hybridization with the E uropean cherry fruit fly. Although mt DNA sequence genealogy could not separate the two A merican species, cross‐species amplification of 14 microsatellite loci separated them with high probabilities (0.99–1.0) and provided evidence for R . cingulata in E urope. G erman and H ungarian R . cingulata populations differed significantly in microsatellite allele frequencies, mt DNA haplotype and wing pattern distributions, and both were genetically depauperate relative to N orth A merican populations. The diversity suggests independent founding events in G ermany and H ungary. Within each country, R . cingulata displayed little or no structure in any trait, which agrees with rapid local range expansions. In cross‐species amplifications, signals of hybridization between R . cerasi and R . cingulata were found in 2% of R . cingulata individuals and in 3% of R . cerasi . All putative hybrids had R . cerasi mt DNA indicating that the original between‐species mating involved R . cerasi females and R . cingulata males.