Alien insect dispersal mediated by the global movement of commodities

Globalization and economic growth are recognized as key drivers of
biological invasions. Alien species have become a feature of almost every
biological community worldwide, and rates of new introductions continue to
rise as the movement of people and goods accelerates. Insects are among
the most numerous and problematic alien organisms, and are mainly
introduced unintentionally with imported cargo or arriving passengers.
However, the processes occurring prior to insect introductions remain
poorly understood. We used a unique dataset of 1,902,392 border
interception records from inspections at air, land and maritime ports in
Australia, New Zealand, Europe, Japan, the United States of America and
Canada to identify key commodities associated with insect movement through
trade and travel. A total of 8,939 species were intercepted, and commodity
association data were available for 1,242 species recorded between 1960
and 2019. We used rarefaction and extrapolation methods to estimate the
total species richness and diversity associated with different commodity
types. Plant and wood products were the main commodities associated with
insect movement across cargo, passenger baggage and international mail.
Furthermore, certain species were mainly associated with specific
commodities within these, and other broad categories. More closely related
species tended to share similar commodity associations, but this occurred
largely at the genus level rather than within orders or families. These
similarities within genera can potentially inform pathway management of
new alien species. Combining interception records across regions provides
a unique window into the unintentional movement of insects, and provides
valuable information on establishment risks associated with different
commodity types and pathways.