The other 99%: exploring the arthropod species diversity of Bukit Timah Nature Reserve, Singapore

Abstract

Bukit Timah Nature Reserve (BTNR) is one of Singapore's most important conservation areas because it is likely to be the last refuge for many species that belong to Singapore's original forest biodiversity. We report here the results obtained from a first broad-scale survey of arthropods in BTNR. The focus was on insects because Singapore's insect fauna remains largely unknown despite the fact that insects constitute much of the animal biomass and perform many ecologically important tasks. The survey relied on specimens collected with passive traps (e.g., Malaise traps) that were set along several transects in primary and different types of secondary forests. Specimens representing several thousand species were obtained. In order to process the specimens rapidly, we sorted them based on DNA sequences of the COI gene. Sequences for more than 9,000 specimens were obtained and the DNA data were used to group the specimens into putative species. Here, we compare the species numbers, composition, and species overlap between secondary and primary forests for "true bugs" (Hemiptera). Overall, the sequences belonged to more than 1850 insect species of which ca. 450 belonged to Hemiptera. A very large proportion of the "true bug" species are only represented by 1 or 2 specimens each and we find that BTNR's species diversity is much higher than the diversity in mangroves and on the National University of Singapore (NUS) campus. We also report and illustrate some notable insect species found during the survey. They range from ship-timber beetles to beetle-flies mimicking leaf beetles and mantis-flies resembling praying mantises.

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