Improvement in the Identification Technology for Asian Spongy Moth, Lymantria dispar Linnaeus, 1758 (Lepidoptera: Erebidae) Based on SS-COI

SIMPLE SUMMARY: Preventing invasion of the Asian spongy moth (ASM) is a major priority for quarantine agencies in North America and elsewhere due to the significant damage and invasiveness of ASMs. ASMs are native to China and strict quarantine procedures have been implemented to prevent unintentional introductions of ASMs to other countries. As there are many closely related species in Lymantria (Hübner, 1819) that are morphologically similar to ASM, especially at immature stages, it is not always possible to determine accurately with morphology. Molecular techniques for rapid detection are, therefore, becoming an immediate need. The main procedures that have been used to identify ASMs are based on samples that have been under artificial culture for dozens of generations, and the artificial culture of these samples might have resulted in the appearance of genetic features that differ from those of natural populations. Moreover, sampling has only been conducted in a few locations in China; given that high genetic variation has been detected in ASMs from different regions in China in recent years, the current methods used for identifying ASMs are not sufficiently robust. In this study, we provide an updated method based on cytochrome oxidase I to enhance the efficacy of ASM identification. This improved approach permits identifications of ASMs to be made in 2–3 h using as little as 30 pg of genomic DNA. This method could, thus, be used to monitor the spread of ASM in real time and mitigate identification errors. ABSTRACT: Lymantria dispar (Linnaeus, 1758), which is commonly known as spongy moth, with two subspecies, is found in Asia: Lymantria dispar asiatica and Lymantria dispar japonica, collectively referred to as the Asian spongy moth (ASM). The subspecies Lymantria dispar dispar occurs in Europe and is commonly known as the European spongy moth (ESM). The ASM is on the quarantine list of many countries because it induces greater economic losses than the ESM. Accurate identification is essential to prevent the invasion of ASM into new areas. Although several techniques for identifying ASMs have been developed, the recent discovery of complex patterns of genetic variation among ASMs in China as well as new subspecies in some areas has necessitated the development of new, improved identification techniques, as previously developed techniques are unable to accurately identify ASMs from all regions in China. Here, we demonstrate the efficacy of an improved technique for the identification of the ASM using ASM-specific primers, which were designed based on cytochrome oxidase I sequences from samples obtained from all sites where ASMs have been documented to occur in China. We show that these primers are effective for identifying a single ASM at all life stages and from all ASM populations in China, and the minimum detectable concentration of genomic DNA was 30 pg. The inclusion of other Lymantria samples in our analysis confirmed the high specificity of the primers. Our improved technique allows the spread of ASMs to be monitored in real time and will help mitigate the spread of ASMs to other areas.