Genetic diversity of Bactrocera dorsalis (Diptera: Tephritidae) on the Hawaiian Islands: Implications for an introduction pathway into California

Abstract

Population genetic diversity of the oriental fruit fy, Bactrocera dorsalis (Hendel), on the Hawaiian islands of Oahu, Maui, Kauai, and Hawaii (the Big Island) was estimated using DNA sequences of the mitochondrial cytochrome c oxidase subunit I gene. In total, 932 fies representing 36 sampled sites across the four islands were sequenced for a 1,500-bp fragment of the gene named the C1500 marker. Genetic variation was low on the Hawaiian Islands with >96% of fies having just two haplotypes: C1500-Haplotype 1 (63.2%) or C1500-Haplotype 2 (33.3%). The other 33 fies (3.5%) had haplotypes similar to the two dominant haplotypes. No population structure was detected among the islands or within islands. The two haplotypes were present at similar frequencies at each sample site, suggesting that fies on the various islands can be considered one population. Comparison of the Hawaiian data set to DNA sequences of 165 fies from outbreaks in California between 2006 and 2012 indicates that a single-source introduction pathway of Hawaiian origin cannot explain many of the fies in California. Hawaii, however, could not be excluded as a maternal source for 69 fies. There was no clear geographic association for Hawaiian or non-Hawaiian haplotypes in the Bay Area or Los Angeles Basin over time. This suggests that California experienced multiple, independent introductions from different sources.