Invasive species have caused severe impacts on biodiversity and human society. Although the estimation of environmental impacts caused by invasive species has increased in recent years, economic losses associated with biological invasions are only sporadically estimated in space and time. In this study, we synthesized the losses incurred by invasions in Asia, based on the most comprehensive database of economic costs of invasive species worldwide, including 560 cost records for 88 invasive species in 22 countries. We also assessed the differences in economic costs across taxonomic groups, geographical regions and impacted sectors, and further identified the major gaps of current knowledge in Asia. Reported economic costs of biological invasions were estimated between 1965 and 2017, and reached a total of US$ 432.6 billion (2017 value), with dramatic increases in 2000–2002 and in 2004. The highest costs were recorded for terrestrial ectotherms, for species estimated in South Asia, and for species estimated at the country level, and were related to more than one impacted sector. Two taxonomic groups with the highest reported costs were insects and mammals, and two countries with the highest costs were India and China. Non-English data covered all of 12 taxonomic groups, whereas English data only covered six groups, highlighting the importance of considering data from non-English sources to have a more comprehensive estimation of economic costs associated with biological invasions. However, we found that the estimation of economic costs was lacking for most Asian countries and for more than 96% of introduced species in Asia. Further, the estimation is heavily biased towards insects and mammals and is very limited concerning expenditures on invasion management. To optimize the allocation of limited resources, there is an important need to better and more widely study the economic costs of invasive alien species. In this way, improved cost reporting and more collaborations between scientists and stakeholders are needed across Asia.

Hainan Island is located within the Indo-Burma global biodiversity hotspot, however, the freshwater fish fauna on this island is poorly understood. Based on field investigations and literature review, we compiled a list of 154 freshwater fish species (138 native and 16 non-native) belonging to 10 orders, 31 families and 104 genera found on Hainan Island. Of these, 31 species are endemic to China. The native freshwater fish fauna in Hainan Island is affiliated to South China sub-region of the Oriental Region. Current knowledge suggests that overexploitation, water pollution, flow modification, habitat degradation, and non-native species have severely reduced the freshwater fish biodiversity in Hainan Island. To protect freshwater fish biodiversity and fisheries in Hainan Island, some new measures should be adopted and current measures better enforced. This study constitutes an important resource for conservation management of freshwater fishes in Hainan Island.