Plant-derived environmental DNA complements diversity estimates from
traditional arthropod monitoring methods but outperforms them detecting
plant-arthropod interactions
Abstract
Our limited knowledge about the ecological drivers of global arthropod
decline highlights the urgent need for more effective biodiversity
monitoring approaches. Monitoring of arthropods is commonly performed
using passive trapping devices, which reliably recover diverse
communities, but provide little ecological information on the sampled
taxa. Especially the manifold interactions of arthropods with plants are
barely understood. A promising strategy to overcome this shortfall is
environmental DNA (eDNA) metabarcoding of arthropods from plant material
they have interacted with. However, the accuracy of this approach has
not been sufficiently tested. In four experiments, we exhaustively test
the comparative performance of plant-derived eDNA from surface washes of
plants and homogenized plant material against traditional monitoring
approaches. We show that the recovered communities of plant-derived eDNA
and traditional approaches only partly overlap, with eDNA recovering
various additional cryptic taxa. This suggests eDNA as a useful
complementary tool to traditional monitoring. Despite the differences in
recovered taxa, estimates of community α- and β-diversity between both
approaches are well correlated, highlighting the utility of eDNA as a
broad scale tool for community monitoring. Last, eDNA outperforms
traditional approaches in the recovery of plant-specific arthropod
communities. Unlike traditional monitoring, eDNA revealed fine-scaled
community differentiation between individual plants and even within
plant compartments. Especially specialized herbivores are better
recovered with eDNA. Our results highlight the value of plant derived
eDNA analysis for large-scale biodiversity assessments that include
information about community level interactions.