Data from: Seeing is believing? comparing plant-herbivore networks constructed by field co-occurrence and DNA barcoding methods for gaining insights into network structures

Plant-herbivore interaction networks provide information about community
organization. Two methods are currently used to document pairwise
interactions among plants and insect herbivores. One is the traditional
method that collects plant-herbivore interaction data by field observation
of insect occurrence on host plants. The other is the increasing
application of newly developed molecular techniques based on DNA barcodes
to the analysis of gut contents. The second method is more appealing
because it documents realized interactions. To construct complete
networks, each technique of network construction is urgent to be assessed.
We addressed this question by comparing the effectiveness and reliability
of the two methods in constructing plant-Lepidoptera larval network in a
50 ha subtropical forest in China. Our results showed that the accuracy of
diet identification by observation method increased with the number of
observed insect occurrences on food plants. In contrast, the molecular
method using three plant DNA markers were able to identify food residues
for 35.6% larvae and correctly resolved 77.3% plant (diet) species.
Network analysis showed molecular networks had three-fold more unique host
plant species but fewer links than the traditional networks had. The
molecular method detected plants that were not sampled by the traditional
method, e.g., bamboos, bryophytes and lianas in the diets of insect
herbivores. The two networks also possessed significantly different
structural properties. Our study indicates the traditional observation of
co-occurrence is inadequate, while molecular method can provide higher
species resolution of ecological interactions.