Rapid and highly accurate detection of Drosophila suzukii, spotted wing Drosophila (Diptera: Drosophilidae) by loop-mediated isothermal amplification assays

Authors: KIM, YOUNG HA - Hallym University; HUR, JOON HAENG - Hallym University; LEE, GWAN SEOK - National Academy Of Agricultural Science; Choi, Man-Yeon; KOH, YOUNG HO - Hallym University

Submitted to: Journal of Asia-Pacific Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2016
Publication Date: 11/3/2016
Citation: Kim, Y., Hur, J., Lee, G., Choi, M.Y., Koh, Y. 2016. Rapid and highly accurate detection of Drosophila suzukii, spotted wing Drosophila (Diptera: Drosophilidae) by loop-mediated isothermal amplification assays. Journal of Asia-Pacific Entomology. 19(4):1211-1216. doi: 10.1016/j.aspen.2016.10.015

Interpretive Summary: Spotted wing drosophila (SWD), Drosophila suzukii, is a destructive invasive pest introduced from Asia, and attacks a wide range of ripening fruits including all cherry crops. Since the first outbreak in California 2008, the distribution of SWD is rapidly expanding across the U.S., Canada and Europe. The estimated economic impact from crop yield loss, drop in market value, and higher management costs is hundreds of millions of dollars in the U.S. alone, and increasing every year. Recently, SWD management has been ranked a top research priority by small fruit growers. To replace or reduce the use of chemical insecticides, alternative options are currently being developed, but there are still many critical gaps to be implemented against SWD in field. Early detection and identification technology enhancement is critical to prevent introduction of exotic species and establishment of exotic and native pests which would result in costly control measures. Using specific genes from target pests including arthropods and disease causing organisms, a loop-mediated isothermal amplification (LAMP) method has been developed to efficiently and rapidly detect a target nucleic acid with high specificity under isothermal conditions. This technology provides high sensitivity (~fg level) and rapid turn around (incubation for 10 – 30 min in a water bath), and does not require sophisticated equipment such as PCR. Therefore, LAMP technology is now widely applied in many fields for on-site detection because of its low cost, high specificity, efficiency, simplicity of operation, rapidness, and ability to be used in broad applications, such as disease diagnosis and food safety testing. Scientists from USDA-ARS at Corvallis, OR, and Hallym University from South Korea developed a novel molecular diagnostic method to detect SWD specific only. This early and identification technology provides to prevent damage from SWD and reduce the management cost in the field.

Technical Abstract: Drosophila suzukii, the spotted wing drosophila (SWD), is currently a major pest that causes severe economic losses to thin-skinned, small fruit growers in North America and Europe. The monitoring and early detection of SWD in the field is of the utmost importance for its proper management. Although SWD traps using various attractants have been developed and used for SWD monitoring in the field, they are not specific to SWD; consequently, other insects, including Drosophilidae flies that share high morphological similarities with SWD, are also easily trapped. Thus, all captured flies need to be identified under microscopes by an expert in fly morphological characteristics. In this study, we developed a simple molecular detection tool that rapidly and accurately identifies SWD without sophisticated instruments or expertise. We first identified a gene, Ds10_00012111, that is present in the SWD genome but not in that of any other insect species. Then, we developed the loop-mediated isothermal amplification (LAMP) assay, which was designed based on genomic DNA of the Ds10_00012111 gene. This LAMP assay detected only genomic DNA from SWD—not from Drosophila melanogaster. The minimum amount of genomic DNA required for the LAMP assay was 1.0 picogram, and the duration of this assay at temperatures ranging from 58 oC to 62 oC was 30 min. In addition, this assay could detect genomic DNA in SWD geographical strains collected from 8 different locations in Asia, Europe, Hawaii, and the USA. Our LAMP assay could be a useful detection tool for identifying SWD rapidly in the field.