Status of invasive alien insects of nationwide survey in South Korea

In this study, we analysed the regional distribution status, species composition differences, seasonal occurrence and habitat types of invasive alien insects that are distirbuted in natural ecosystems nationwide, targeting 3,802 locations in eight regions between 2019 and 2021. A total of 95,017 invasive alien insects belonging to nine orders, 48 families and 77 species were identified. Amongst the taxonomic groups, Hemiptera (35.1%) was dominant, followed by Coleoptera (18.2%) and Lepidoptera (14.3%). Gyeongsangnam-do had the highest percentage of invasive alien insects, with 55 species, while Gyeonggi-do had the highest number of invasive alien insects at 890 sites. We used Non-metric multidimensional scaling (NMDS) to analyse differences in invasive alien insect species composition by region, occurrence by season and habitat type. To compare the differences in invasive alien insect species composition by region, we divided them into four groups (Group 1: Jeollanam-do, Jeollabuk-do; Group 2: Chungcheongnam-do, Chungcheongbuk-do; Group 3: Gyeongsangnam-do, Gyeongsangbuk-do; and Group 4: Gyeonggi-do, Gangwon-do). We found an extensive overlap in invasive alien insects composition by region. Additionally, species composition exhibited seasonal differences, with the highest number of invasive alien insects occurring between July and September. Species occurring in spring (April to May) included Dryocosmus kuriphilus, Hypera postica and Brachypera zoilus, whereas those occurring in autumn (September to October) included Vespa velutina nigrithorax, Thecodiplosis japonensis and Hermetia illucens. Habitat type analysis showed that invasive alien insects lived along roadsides (31.9%), farmlands (27.9%) and parks (19.4%), exhibiting high densities in anthropogenic and disturbed sites, such as parks, residences and farmlands. Ecological statistical analysis showed that the dominance index was 0.6 in Chungcheongbuk-do, the diversity index was 2.7 in Gyeongsangbuk-do, the abundance index was 5.4 in Gyeongsnagnam-do and the equality index was 0.6-0.7 in all regions. Therefore, we aimed to identify the habitat status of introduced and settled invasive insects to provide a basis for selecting primary management target species.