Differing interactions between an introduced beetle and a resident root nematode mediated by an invasive plant and its native congener

Abstract

Interactions between above- and below-ground herbivores play an important role in shaping plant competition and invasion, while the effects of non-native species invasions on above- and below-ground interactions remain unexplored. In this study, we report the interactions between an above-ground introduced beetle and a resident root nematode hosted by an invasive plant or its native congener with a laboratory bioassay and a greenhouse experiment in Wuhan, China. Nematode infections decreased beetle food conversion rates and larval biomass on the native plant, and increased beetle food conversion rates with no detectable impact on the larval biomass on the invasive plant. Beetle defoliation decreased nematode egg production on both the native and invasive plants. The interactions of the introduced beetle and the nematode were different by the invasive and native plants, which suggests that invasive plants and their introduced herbivores have the potential to alter above- and below-ground interactions and affect associated community members, which may in turn affect invasion processes and the safety of classical biocontrol practices.