University of São Paulo: Vertical Biodiversity: Scientists Explore Uncharted World of Insects in the Amazon Treetops

If you already knew that the biodiversity of the Amazon is enormous, know now that it is even greater than you imagined. In a pioneering study, scientists placed insect traps along several floors of a 53-meter tower in the middle of the Amazon rainforest near Manaus. Two weeks later, they returned to see what they had collected and the result was impressive: almost 38,000 insects, from 18 different orders, including flies, bees, beetles, butterflies and other groups less known to the general public, but of great importance to the ecological balance of the forest. Even more surprising was the vertical distribution of this biodiversity: almost 70% of the insects were collected above 8 meters in height, and about 90% of them are from species not yet described by science.

“It’s as if there were another continent above our heads,” entomologist (insect specialist) Dalton de Souza Amorim, from the Department of Biology at the Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP) at Ribeirão Preto , told Jornal da USP . USP. He is the first author of the paper that describes the findings of the experiment, published on February 2nd in Scientific Reports, in collaboration with several colleagues from Brazil and abroad. “More than half of the insect fauna is up there, in the tops of the trees”, he summarizes, in a mixture of excitement and admiration for what he discovered. “Above 32 meters is crazy; that over there is an avenue.”

The researchers knew that the insect biodiversity of the canopy (the ecosystem formed by the set of treetops) would be different from that found on the forest floor. No surprises there. Several studies of this type have been carried out in the past, in various parts of the world, targeting specific groups of insects or collecting specimens in a more general way – for example, through the fumigation of trees, when a steam insecticide is applied to knock the insects down. from the canopy and collect them on the ground. “But this had never been analyzed in such a structured and systematic way”, highlights Amorim.

In this case, the traps, similar to a transparent screen tent, with 6 meters (m) in length each, were installed on five floors of the research tower, with 8 meters of vertical distance between them (0.8, 16, 24 and 32 meters above ground level). The tower, known as ZF2, belongs to the National Institute for Research in the Amazon (Inpa) and is located at the Experimental Station for Tropical Silviculture, about 60 kilometers (km) north of Manaus, in a region of dense and well-preserved forest, where the average crown height is 28 meters — but there are trees that reach 50 meters. (See the exact location of the tower via Google Maps, here .)

This unprecedented configuration allowed the scientists not only to make a comparison between the soil and the canopy, but also to stratify the samples according to the height at which each insect was captured within the canopy. “We started to gain a better understanding of the vertical structure of forest biodiversity”, celebrates Amorim. It became clear that not only the fauna that circulates through the canopy is different from that which lives close to the ground, but that each “floor” of the forest has its particularities. Not all insects that circle 8 meters above the ground reach the tops of trees, and not all insects that live 32 meters high descend to the forest floor, for example — “illustrating the importance of the canopy as a set of distinct habitats” , with varied niches for insects,” the researchers write in Scientific Reports. The experiment was conceived by entomologist José Albertino Rafael, from Inpa, who also signed the study.

According to Amorim, about 23% of the species collected in the experiment were exclusive to the soil — that is, they did not appear in any of the canopy samples — while 60% were present only in the canopy. Only 17% of the species were recorded both on the ground (below 8 meters) and in the canopy (in any of the layers above 8 meters).

The collections took place over a period of two weeks, in August 2017. Separating into rounded numbers, 16,600 specimens of Diptera (flies and mosquitoes), 7,300 specimens of Hymenoptera (bees, wasps and ants), 6,900 Lepidoptera (butterflies) were captured. and moths), 3,940 hemipterans (cicadas, leafhoppers, bedbugs, barbers and others) and 2,670 beetles (beetles and ladybirds). And that was just the beginning! After this first collection effort, described in the current work, Rafael and his team in Manaus continued setting up the traps in the tower for another 13 months, resulting in a collection of approximately 700,000 insects, which will still take years (probably decades) to be sorted. and analyzed in full.

The amount and diversity of insects collected in those first two weeks alone were so great that until today, more than four years after the beginning of the experiment, scientists have not yet been able to identify all the families represented in the material. Much less all species. (Remembering that living beings are classified into kingdoms, phyla, classes, orders, families, genera and species. We modern humans, for example, belong to the kingdom Animalia, phylum Chordata, class Mammalia, order Primate, family Hominidae, genus Homo, species Homo sapiens .)

The group that received the most attention was the Diptera (order Diptera), a specialty of Amorim and Rafael. Samples of flies and mosquitoes collected from the tower were shared with several experts, resulting in the identification of 856 species — or “morphospecies,” more specifically, which is when an organism is classified based solely on its morphological, not genetic, characteristics. Most have been identified down to the genus level, and are likely to represent new species to science. Some are likely new genera, and there are still those that have not even had their families identified, for lack of specialists. In other words, there is still a lot of work ahead.

Describing these small insects, represented by hundreds or even thousands of species, is “our biggest challenge in understanding biodiversity”, says Amorim. The next big project he wants to put into practice involves the use of a technique known as DNA barcoding , which allows species to be identified quickly and with great accuracy, through their genetic information – which would be extremely useful for analyzing large volumes. of biological material, such as this collected in the tower.

Importance
But why so much effort to identify flies and mosquitoes? Most people, given the choice, would probably prefer to get rid of them and all other insects in nature—with the exception, perhaps, of butterflies. But be very careful with what you wish for, because without these small invertebrates to perform a multitude of extremely important ecological services (such as pollination of flowers and the decomposition of organic matter), the forest as we know it would simply not exist. “Without the insects, the system collapses”, summarizes Amorim. Every species has its role in the ecosystem, and insects are by far the most numerous and diverse group of fauna on the planet.

In this sense, knowing and protecting the biodiversity of flies, ants and beetles in the Amazon is as important for the future of the forest as studying and preserving its jaguars and macaws. The results of the study, according to the authors, are a warning that the amount of biological diversity that is lost with deforestation — or even with the selective extraction of large trees, essential for the structure of the canopy — is even greater than previously thought. .

“Considering the enormous pressure on the Amazon primary forest in recent years, in some cases even carried out with government support, understanding its biodiversity becomes a more urgent priority. This cannot be achieved in a ‘data vacuum’. This work fills part of this gap, demonstrating a rich and unique canopy fauna and a complex system of vertical patterns of different groups of insects in the Amazon rainforest. And they end with an appeal: “Concerted action must be taken to protect tropical ecosystems – including all canopy levels – against widespread stressors such as climate change, deforestation, landscape fragmentation and pesticide use.”

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