Asteraceae-Herbivore interaction network

Associations between Asteraceae and flower-head endophagous insects were assessed quantitatively in 20 remnants of Cerrado vegetation in southeastern Brazil (Almeida-Neto et al. 2011).The sampled sites were spaced from 0.6 to 41.4 km apart (mean distance = 16.3 km), at elevations ranging from 600 to 950 m. Plants and insects were sampled from April to May 2003. The sampling design consisted of 15 transects of 30m × 5m, randomly allocated in relation to the edge of the areas. We sampled flower heads from at least 20 individuals of each Asteraceae species, collecting about 80 mL of flower-heads per individual plant whenever available. In the laboratory, the flower-head samples were kept in plastic containers covered with a mesh lid. Adult herbivore emergence was checked at least weekly for a period of two months. We spent about four person-hours collecting flower-heads in each period and site. Further information on sampling, vegetation, and studied areas can be found in Almeida-Neto et al. (2010, 2011).
For the purpose of this study, both species and their interactions were integrated into a single regional plant-herbivore network, depicting the presence or absence of interactions between each plant-herbivore pair. We only included in the regional interaction network the plant and insect species that occurred in at least five (25%) of the sampled areas. By constructing the network in this way, we aimed to minimize the effect of spatial mismatch on the structure of plant-herbivore interactions. Among the 1210 plant-herbivore pairs included in our network, only 12 do not co-occur in at least one site.