Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2015
Publication Date: 6/1/2015
Citation: Murphy, K.A., Unruh, T.R., Zalom, F.G., Shearer, P.W., Beers, E.H., Chiu, J.C. 2015. Using comparative genomics to develop a molecular diagnosis for the identification of an emerging pest Drosophila suzukii. Bulletin of Entomological Research. 105(3):364-372. Interpretive Summary: Drosophila suzukii, the spotted wing Drosophila (SWD), is a recent invader of the United States and is a potentially serious pest of soft fruits and vegetables throughout the country. In Washington State, it is attacking cherries, grapes, blueberries and peaches. This insect is a pest of quarantine significance for USA growers that export to trading partners in the southern hemisphere. The immature stages of SWD are morphologically indistinguishable from other species of Drosophila that are not of quarantine importance but may still be found in soft fruits. Hence, the fruit industry needs a method to identify SWD from all other Drosophila species. Researchers at the USDA ARS Yakima Agricultural Research Laboratory, Wapato WA, together with colleagues from University of California at Davis, Oregon State University and Washington State University, developed a DNA-based method to identify SWD. A novel method of gene discovery was employed to discover a distinct region of the SWD genome that was unique compared to the other non-pest Drosphila species. This method to identify immature stages of SWD should reduce quarantine concerns by avoiding export of SWD-infested fruits.
Technical Abstract: Drosophilia suzukii (Spotted Wing Drosophila) has recently become a serious invasive pest of fruit crops in the U.S., Canada, and Europe, leading to substantial economic losses. D. suzukii oviposits directly into ripe or ripening fruits making it a direct pest; in contrast, other Drosophilids utilize rotten or decaying fruits and are nuisance pests at worst. Immature stages of D. suzukii are difficult to differentiate from other drosophilids, which poses a problem for research, and meeting quarantine restrictions for fruit export that are designed to prevent further spread of this pest. Here we present a molecular diagnostic for rapid identification of single D. suzukii larva using multiplex polymerase chain reaction (PCR). Our molecular diagnostic was validated using ten different species of Drosophila for specificity and eleven wild populations of D. suzukii from different geographical regions to ensure utility within species. We present the first use of a combined bioinformatics and phylogenetic approaches to discovery of a gene suitable for a species diagnostic protocol of an agricultural pest.