Quantitative food webs of dipteran leafminers and their parasitoids in Argentina

The quantitative structure of two host-parasitoid communities based on leaf-mining flies (Diptera, Agromyzidae) in Argentina is described. The two communities consisted of 29 and 27 hosts, 46 and 40 parasitoids, and 193 and 179 recorded host-parasitoid associations. Also, food webs were constructed for one community based solely on samples taken in the wet and dry seasons. Data were expressed as quantitative food webs, and the manner in which food web properties, such as connectance and compartmentalization, were influenced by sampling intensity was explored. The potential importance of indirect effects between hosts mediated by parasitoids (e.g. apparent competition) was assessed using quantitative parasitoid overlap diagrams. The study's results suggest that indirect effects are likely to be important in these highly connected communities. The limitations of the study's analysis, and how the conclusions can be tested experimentally, are discussed.