The Global Exchange and Accumulation of Alien Insect Species

Humans have translocated thousands of species, either intentionally or not, from their native ranges to non-native ones, with many established (naturalized) and some now invasive. We report here a global database on the distributions of naturalized alien insects. Currently, 7,741 naturalized alien insect species have been reported from 222 regions, of which 47 species were reported over all six continents, 103 species over five continents, and 208 species over four continents. Naturalized alien insects are taxonomically diverse in all six continents, predominantly occurring in agroecosystems, as well as forests and grasslands. North America has accumulated the greatest number of naturalized alien insect species, while South America has the lowest number. Asia donated the greatest number of its native insect species to other continents, especially to North America and Europe. The global patterns of naturalized alien insects are correlated with transcontinental trade and the number of local scientists who study insect invasions. Most naturalized alien insects have been introduced to multiple continents, further facilitating the expansion of introduced populations through bridgehead effects. Understanding the global exchange and accumulation of alien insects helps the development of an early warning and monitoring system for insect invasions.