Arthropod communities in the spider diet differ between
native and invaded sites,
Our results show that in areas modified by invasive ginger, spiders are
consuming a very different, but partially overlapping, spectrum of prey
items compared to spiders in native forest (Figure 4). Spiders in native
forest are preying predominantly on Hemipterans and show a narrow
selection of prey while the diets of spiders in ginger are more varied,
and consist of prey orders uncommonly found in the diets of spiders
collected from native forest (Figure 5). In invaded sites, a more
diverse prey community was detected in totality, reflected in the
individual diets of spiders as well which showed wider breadth than
spiders from native sites. Trophic dispersion has been detected in other
studies following invasion, which can be followed by destabilization of
the food network (Wainright et al. 2021).
Spiders in ginger also appear to be consuming more prey, when using
sequencing reads as a proxy measurement for abundance (Figure 2).
Invasive plants have been found to increase the abundance of available
arthropods that can serve as prey in some studies. For example, a study
in the Iberian Peninsula found a much higher abundance of generalist
herbivore species on nonnative plants (RodrÃguez et al. 2019).
This increase may partially be due to the provision of shelter (Landsmanet al. 2020). A similar result was found for arthropods
associated with invasive tamarisk in Colorado (Uhey et al. 2020).
Spiders make site settlement decisions based on multiple factors,
predominantly microhabitat and prey availability (Riechert & Gillespie
1986). If there is abundant potential prey and if ginger provides
additional protection through the dense plant structure, spiders may
perceive the habitat to be highly suitable (Gillespie & Tabashnik
1994). However, unpublished data from arthropod sampling in this
invasion of ginger did not detect higher densities of arthropod prey.
The higher reads in the diets of spiders in ginger may then point
towards suboptimal prey, where the spiders must consume more prey to
meet their nutritional requirements.