Hunting bugs in Panama: Raphael rafts the treetops for biodiversity

Dangling from ropes and clinging to a giant raft suspended in the treetops of Panamanian rainforests might sound like the realm of Indiana Jones, but for one of our researchers it’s just a matter of course in the pursuit of biodiversity knowledge.

Professor Raphael Didham, a joint appointee with CSIRO Ecosystem Sciences and the University of Western Australia, has been part of an international team scaling new heights in the mapping of bug (arthropod) biodiversity.

Raphael ‘rafting’ high in the canopy of a Panamanian forest.

The team that Raphael is a part of has just published in the journal Science (it’s featured on the cover in fact!) some astounding figures about the diversity and abundance of arthropods (bugs that include insects, spiders, millipedes, centipedes and crustaceans). Compared to other forms of life in the rainforest they are very diverse indeed.

“Based on our research we were able to quantify the dominant role that arthropods play in biodiversity and the web of life,” said Raphael.

“We calculated that around 25,000 species of arthropod live in a 6000 hectare tropical rainforest and that was about 20 times the number of plant species, 83 times the number of bird species and 312 times the number of mammal species.”

To come up with those figures the international team of 102 researchers from 21 countries put in an unprecedented effort over nearly ten years, including two years of sampling, and eight years of sorting through and identifying 130,000 bugs.

Arachnoscelis magnifica: a canopy-dwelling long-horned cricket (grasshopper). In the sun-mottled upper areas of the canopy, the bright colours act to break up the outline of the animal and make it difficult for predators to detect it. Beautiful enough to make the cover of Science. Photo: Maurice Leponce, Royal Belgian Institute of Natural Sciences.

“At times it was more like the set of an Indiana Jones movie,” Raphael said.

“Together we spent nearly 70 person years atop cranes, balloons and inflatable pontoons in the canopy, dangling off ropes in the forest layers, and sifting through soil and litter while crawling across the forest floor.”

A villain tries to shoot down our hero Raphael… Just kidding! This is a process called ‘fogging’, which causes the insects to lose hold of the leaves and fall onto large collecting sheets positioned on the forest floor below. Photo: R. Le Guen.

The researchers intensively sampled 12 sites in Panama’s San Lorenzo forest and used their findings to ‘scale-up’ an understanding of rainforest biodiversity across the region.

“We found that a surprisingly large proportion (about 60%) of all species in the region could be detected within a single hectare of forest, which means it is possible to scale-up results from a relatively small sampling area.”

“Most importantly, we also found that patterns of plant diversity across a region correspond closely with levels of arthropod diversity and can be used to predict it. This adds support to a focus on conserving plant diversity and, along with it, arthropod diversity.”

Raphael and his CSIRO colleagues are now exploring new ways of mapping regional biodiversity that are less resource-intensive and time-consuming.

Check out the UWA media release and have a look at the research here on Science.

Aerial view of the canopy raft, which is used as a platform from which to work and to camp overnight. It allows researchers to collect insects from the very outer layers of the canopy foliage, as well as abseil down through different vertical layers of vegetation below. It is made of inflatable pontoons and kevlar webbing, and can be flown in by a dirigible, or heavy-lifting helicopter. Photo: R. Le Guen.