GoKawiilA juvenile female of the mantid species Choeradodis rhomboidea was collected as part of an effort to catalog insects in the Amazon.Credit: Bernardo Ferraz/BioInsecta
The Amazon’s lush rainforest harbours a hidden world of tiny creatures, nearly all of them unknown to science. But now hundreds of scientists in Brazil are collaborating on a quest to count every species of insect in one expanse of the Amazon — the largest insect-biodiversity study to ever explore the forest from the ground to the canopy.
Preliminary data suggest that the number of insect species could surpass 40,000, which is almost 0.7% of the widely accepted estimate of 6 million living insect species worldwide. And that 40,000 figure is for a single location in the Amazon. “If we start sampling other parts of the forest, the number of new species will likely increase almost exponentially,” says José Rafael, an entomologist at the National Institute for Amazonian Research (INPA) in Manaus, Brazil, and one of the scientists leading the megaproject.
Unpicking the rhythms of the Amazon rainforest
The project is unique, says Rudolf Meier, an entomologist at the Museum of Natural History in Berlin, because it is collecting insects high above the ground, in layers that have remained largely unexplored. He adds that the megaproject is also one of the largest to use DNA barcoding in insects, a method which identifies a species on the basis of a short fragment of its DNA, enabling researchers to sequence parts of the genome of thousands of specimens in a small amount of time.
An overview of the campaign was presented in a video poster as part of the online programme of the annual meeting of the Brazilian Society for the Advancement of Science in Niterói last week.
Stacks of traps
To collect insects, project scientists have deployed three arrays of traps. Each array consists of five mesh traps arranged in a vertical stack: one on the forest floor, one suspended about 30 metres (roughly the height of a 10-storey building) above it and three more in between. Insects that fly into each trap are funnelled into a collecting bottle at the top. There, they fall into ethanol, which kills the insects while preserving their DNA for analysis.
Researchers are deploying five-level trap systems to find insects from the forest floor to the treetops.Credit: Larissa Queiroz/BioInsecta
The trap systems, which are installed in a 10,000-hectare area of central Amazon in northern Brazil, have collected insects continuously for 14 months. To catch species that would otherwise be missed by this kind of trap, the team organized an insect-collecting ‘blitz’ last November that used around 50 extra collection methods. For example, researchers used rotting meat to attract carrion-feeding flies and beetles, as well as light traps to sample nocturnal insects.
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