Abstract
Earth systems are nearing a global tipping point, beyond which the
dynamics of biological systems will become unstable. One major driver of
instability is species invasion, especially by organisms that act as
“ecosystem engineers” through their modification of abiotic and biotic
factors. In a mosaic landscape of non-invaded and invaded habitat,
ecosystems modified through invasion may serve as “sink” habitat. To
understand how native organisms respond to habitat that is becoming
increasingly modified, it is essential to examine biological communities
within invaded and non-invaded habitat, identifying compositional shifts
between native and non-native taxa as well as measuring how modification
has affected interactions among community members. Using dietary
metabarcoding, our study examines the response of a native Hawaiian
generalist predator to habitat modification by comparing biotic
interactions across metapopulations of spiders collected in native
forest and sites invaded by kahili ginger. Our study shows that,
although there are shared components of the dietary community, spiders
in invaded habitat are eating a less consistent and more diverse diet
consisting of more non-native arthropods which are rarely or entirely
undetected in spiders collected from native forest. Additionally, the
frequency of novel interactions with parasites was significantly higher
in invaded sites, reflected by the frequency and diversity of non-native
Hymenoptera parasites and entomopathogenic fungi. The study highlights
the role of habitat modification driven by an invasive plant in altering
community structure and biotic interactions, appearing to serve as a
“sink” for native arthropods and thereby threatening the stability of
the ecosystem.