Microsatellite Variation of two Pacific CoastDrosophila suzukii(Diptera: Drosophilidae) Populations

Abstract

The vinegar fly, Drosophila suzukii (Diptera: Drosophilidae), is a recent invader in North America that has become a serious threat to small fruit production. It was first detected in California in 2008 and in Washington state in 2009. In this study, D. suzukii populations from the area of the original detection on California's central coast and from eastern Washington, the United States, were sampled over a 3-year period to determine genetic variation in both using microsatellite markers. Six different loci were successfully amplified and included in the analysis. These loci included nanos, elf1, antennapedia, mastermind, z600, and tenA. The population from eastern Washington was highly monomorphic with one locus, mastermind, having multiple alleles. There was greater genetic variation in the coastal California population with all loci having multiple alleles, with the exception of tenA. Owing to the relatively low levels of genetic variation in the eastern Washington population compared with the coastal California population, it appears that the D. suzukii population in the eastern Washington region has undergone a significant bottleneck.

Genetic variability in Italian populations of Drosophila suzukii

“…The high level of heterozygosity could be explained by good adaptation to new ranges due to a favourable environment, their reproductive power, and the absence or limited presence of natural competitors and predators [ 57 , 58 ]. Bahder et al found that populations from Washington were much less polymorphic than those in California, suggesting a recent strong population bottleneck associated to the recent invasion of the former [ 22 ]. Washington has a much cooler climate than California, similar to the contrast between Trentino and the rest of Italy.…”

“…Jeffrey and colleagues based their research on the use of six X-linked genes and suggested that the invasions of the USA and Europe are two independent events [ 21 ]. Bahder et al in particular analysed samples of D. suzukii populations collected in California and Washington and determined that while D. suzukii in the former region had high levels of genetic variation, the latter was highly monomorphic [ 22 ]. Furthermore, Fraimout’s group investigated Hawaiian and Spanish populations by exploiting microsatellite markers, finding a significant level of genetic differentiation [ 23 ].…”

Laboratory studies of insecticide efficacy and resistance inDrosophila suzukii(Matsumura) (Diptera: Drosophilidae) populations from British Columbia, Canada

“…Two aspects could be inferred from the absence of resistance after selection with malathion over 30 generations in SWD: (1) the initial cherry and blueberry collected populations had low genetic variability or (2) the microbial degradation of malathion was facilitated by yeast and bacterial complexes originating from the adults. In the first case, a genetic bottleneck in Pacific northwest populations of SWD has previously been documented and could contribute to the lack of change in malathion susceptibility in recently established BC SWD populations. A selection with contact insecticides under field conditions could induce monogenic resistance by fixing onto the dominant allele through mutations should the SWD genetic reservoirs exist .…”

Optimization of native biocontrol agents, with parasitoids of the invasive pest Drosophila suzukii as an example

“…Throughout the course of the invasion of D. suzukii , its genetic diversity changed through bottlenecks and admixture events (Fraimout et al., ). A comparison of the host genotype across neutral markers (6–28 microsatellites) and six X‐linked loci in coding and noncoding sequences indicated relatively high intraspecific genetic variation within and between populations in the invaded regions (Adrion et al., ; Bahder, Bahder, Hamby, Walsh, & Zalom, ; Fraimout et al., , ). It is therefore reasonable to assume that there is substantial intraspecific genotypic variation in the invaded populations that can contribute to the variable D. suzukii –parasitoid outcome.…”