How to inventory tropical flies (Diptera)—One of the megadiverse orders of insects

Abstract

A new approach to inventory Diptera species in tropical habitats is described. A 150 x 266 m patch of cloud forest at Zurquí de Moravia, Costa Rica (10.047N, 84.008W) at 1585 meters asl was sampled with two Malaise traps for slightly more than one year (Sept. 12, 2012-Oct. 18, 2013. Further concomitant sampling with a variety of trapping methods for three days every month and collecting during a one-week intensive "Diptera Blitz", with 19 collaborators collecting onsite, provided diverse additional samples used in the inventory. Two other Costa Rican sites at Tapantí National Park (9.720N, 83.774W, 1600 m) and Las Alturas (8.951N, 82.834W, 1540 m), 40 and 180 km southeast from Zurquí de Moravia, respectively, were each sampled with a single Malaise trap to allow for beta-diversity assessments. Tapantí National Park was sampled from Oct. 28, 2012-Oct. 13, 2013 and Las Alturas from Oct. 13, 2012-Oct. 13, 2013. A worldwide group of 54 expert systematists are identifying to species level all 72 dipteran families present in the trap samples. Five local technicians sampled and prepared material to the highest curatorial standards, ensuring that collaborator efforts were focused on species identification. This project, currently in its final, third year of operation (to end Sept. 1, 2015), has already recorded 2,348 species and with many more yet expected. Unlike previous All Taxon Biodiversity Inventories, this project has attainable goals and will provide the first complete estimate of species richness for one of the four megadiverse insect orders in a tropical region.Considering that this is the first complete survey of one of the largest orders of insects within any tropical region of the planet, there is clearly great need for a consistent and feasible protocol for sampling the smaller but markedly more diverse smaller insects in such ecosystems. By weight of their species diversity and remarkable divergence of habit, the Diptera are an excellent model to gauge microhabitat diversity within such systems. Our model appears to be the first to provide a protocol that can realistically be expected to provide a portrayal of the true species diversity of a megadiverse order of insects in the tropics.

Remarkable fly (Diptera) diversity in a patch of Costa Rican cloud forest: Why inventory is a vital science

“…Most previous efforts to determine the number of insect species in tropical locations have been swamped by several factors: (1) vastly overestimating the size of the area that could be adequately interpreted and resulting in too many specimens; (2) huge numbers of uncurated (unprepared) specimens (especially of the "difficult" groups); (3) poor organisation for sample processing and dissemination (including lack of care of fragile specimens); (4) a lack of systematists with the expertise to identify the resultant material; (5) constrained funding; (6) or usually, by a combination of these factors (Borkent & Brown 2015). Other more focused efforts, such as the sampling undertaken by Erwin (2004), Erwin & Geraci (2009) and Erwin et al (2005), have projected global diversity levels based on relatively limited samples such as those taken by fogging small patches of trees in the Neotropical Region.…”

“…Identification of the Diptera from a single Malaise trap was considered a minimum contribution by participating systematists. However, in response to initial invitations, all the samples from more extensive collecting methods at this site (Borkent & Brown 2015;Fig. 2) were studied by all coauthors, other than for the hyperabundant Phoridae.…”

“…As expected, the diversity was strikingly high in this relatively small patch of cloud forest. Borkent & Brown (2015) provide a synopsis of why Diptera are particularly suited to biodiversity studies. In summary, Diptera as a group are remarkably diverse at the species level, currently with 159,051 named species (Table 2) and vastly more unnamed, especially in tropical regions.…”

An annotated preliminary list of the Chironomidae (Diptera) of Zurquí, Costa Rica

“…Several technicians (see Borkent & Brown 2015) at INBio sorted material to family; Annia Picado selected specific specimens and prepared the slides. Robin E. Thompson, Curator of the Insect Collection at the University of Minnesota, St. Paul, MN, made important types and other specimens available from the Sublette Collection housed there.…”

“…Fifty-nine collaborators took part in the project; I was fortunate to work with the Chironomidae. Borkent & Brown (2015) provided an overview of the project and its protocol.…”