Novotny, Vojtech and Miller, Scott E. 2014. "Mapping and understanding the diversity of insects in the tropics: past achievements and future directions." Austral Entomology, 53, (3) 259–267. https://doi.org/10.1111/aen.12111.
We still do not know how many insect species there are in tropical forests. The rate of species description peaked a century ago. Unfortunately, taxonomy ceased to be fashionable before it had completed cataloguing insect diversity. Molecular information combined with web-based data dissemination promises to shorten the 20 years it takes on average for insect specimens to be described as new species. Our inability to enumerate tropical species has made estimates of their diversity popular. Plant-based estimates, multiplying the number of plant species by the number of insect species effectively specialized to them, have been used for the past 150 years for global insect diversity estimates and recently also for the first local rainforest diversity estimate of arthropods, at 25 000 species. Why are there so many insect species in tropical forests? Insect diversity may be driven by latitudinal trends in vegetation. The near impossibility of conducting a complete census of complex plant-insect food webs in tropical forests should focus our attention upon the most common species and interactions. Recent studies of trees in Amazonia and herbivores in New Guinea suggest that such reduced food webs may be surprisingly simple and, thus, amenable to study, while still including more than 50% of all plant and insect individuals and their interactions. A pan-tropical network of plots, modelled on the existing network of forest dynamics plots, and potentially utilizing the existing, but rather poorly used, network of canopy cranes, could provide spatially resolved data on plant-insect food webs. The study of food web dynamics requires experimental manipulation, which can range from exclusion or addition of single species to ecosystem-wide manipulation of species composition and habitat fragmentation. Recent progress in molecular taxonomy, proliferation of community phylogenies, improved food web census techniques and an increasing focus on experiments promise an exciting time for tropical entomology.
