Integrative analysis on the hitchhiking differential grasshopper, Melanoplus differentialis (Thomas, 1865) (Acrididae, Orthoptera)

We conducted the monitoring of hitchhiker insect pests around the port area in Korea and reported the settlement of Melanoplus differentialis (Thomas, 1865) in Onsan Port, Ulsan, Korea. The occurrence pattern of the invasive species was determined using a line census method. Species identification was first performed with DNA barcoding, and then the DNA barcoded samples were morphologically re‐examined. Monitoring of the occurrence pattern revealed that the invasive populations of M. differentialis settled in a narrow artificial green area, and it occurred in large numbers (over 100 individuals per hour). Species identification of the invasive population using DNA barcoding indicated that the population showing high intraspecific divergence from null to 3.9% was difficult to identify as a separate species. However, in morphological re‐examination, the population was clearly identified as a single species, M. differentialis. In a haplotype analysis using DNA barcodes, the population included 45 haplotypes with polymorphism at 46 nucleotide sites. On the basis of these results, we considered that M. differentialis may have invaded into Onsan Port, Ulsan, Korea. Therefore, we provided the biological traits of the grasshopper for risk assessment and suggested the necessity of monitoring and controlling the dispersal of M. differentialis into the inlands of Korea in the early stages.