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Plant diversity drives global patterns of insect invasions

During the last two centuries, thousands of insect species have been moved (mostly unintentionally) outside of their native ranges. Some of these species were able to establish in new areas and in some cases with catastrophic ecological and economic impacts. Why have some world regions been invaded by more insect species than others?

This question was addressed by an international team of researchers led by Andrew Liebhold, including C·I·B Associate, Petr Pyšek, who set out to determine how environmental characteristics explain global variation in numbers of non-native insect species. To do this, the team analysed species inventories from 44 land areas, ranging from small oceanic islands to entire continents in various world regions and statistically related the numbers of native and non-native insect species to several different habitat characteristics.

They determined that numbers of invasions were partially explained by human demographics that influence historical trade and travel; this included for example human population density. However, the primary determinant of numbers of insect invasions was plant diversity. Both numbers of native and non-native plants strongly influenced numbers of insect invasions worldwide. These results suggest that areas with rich plant diversity (such as in the tropics) are most prone to future insect invasions and that efforts to control the establishment of invasive non-native plants may have an added benefit of minimizing future insect invasions.

Liebhold described these results: “We weren’t expecting to see this strong influence of plant diversity on insect invasions but in retrospect, it makes sense since most insects are herbivores. More plant species means more opportunities for invading insects to establish and thrive.”




Read the full paper at:

Liebhold, A.M., Yamanaka, T., Roques, A., Augustin, S., Chown. S.L., Brockerhoff, E.G. and Pyšek, P. (2018). Plant diversity drives global patterns of insect invasions. Scientific Reports 8:12095

For more information, contact Andrew Liebhold at aliebhold@gmail.com

Fit of the reduced structural equation model predicting native and non-native plant and insect species richness

Fit of the reduced structural equation model predicting native and non-native plant and insect species richness. Regression parameter estimates are shown next to arrows; black arrows indicate positive estimates, blue arrows indicate negative estimates and weight of each arrow is proportional to the estimated value. Dashed arrows correspond to non-significant relationships. Distance represents insularity and is measured by distance to the mainland. (Figure by Liebhold et al. 2018)