“Insects are extremely important because of their interactions with forest dynamics and with the human populations living within it, yet we know very little about most species and their distribution, especially those that live high in the trees, the least sampled and least studied layer of the Amazon and other biomes,” says Inpa technician Francisco Felipe Xavier Filho – Chico – while removing a trap.
Collecting above ground level requires a higher degree of complexity. The first step toward sampling life at height took place at the ZF-2 tower. “This tower was built in cooperation with Japan in the late 1970s, primarily for meteorological measurements. And since the early 1980s, Inpa researchers have been collecting insects from this forest at different heights. This has already revealed a very distinctive diversity in the Amazon canopy,” explains Dalton Amorim.
In 2017, José Albertino Rafael and his team installed flight-interception traps at multiple levels, on the ground and at 8, 16, 24, and 32 meters. “That was when we truly understood the impact a project like this could have,” Amorim emphasizes.
In that first pilot, with the metal tower, the scientists encountered virtually no obstacles. But with the launch of the two new megaprojects, the goal became to compare different areas, and building a tower at each site would have been prohibitively expensive. “So we had to develop a strategy for stratified sampling. We sketched designs on many sheets of paper, then went into the field to test how to raise the traps,” Rafael recalls.
The researchers targeted emergent trees, those that grow above the main canopy layer, surpassing 30 meters and reaching heights of up to 60 meters, with some recorded at nearly 80. These giants effectively took on the role of the tower, with traps anchored to their strongest branches. “After managing to pass a rope over these branches, we hoisted the traps, which remain suspended at standardized intervals every seven meters, reaching up to 28 meters, the average canopy height in the Central Amazon,” explains the Inpa professor.
When insects hit the trap screens, they fall into collectors filled with absolute alcohol—used to preserve DNA, hanging at the base. After two weeks, when the samples are retrieved, the jars are packed with flies, mosquitoes, crickets, gnats, praying mantises, grasshoppers, horseflies, moths, and many others. Hundreds of thousands of specimens will have part of their DNA sequenced and will then be sent to a wide network of specialists in each insect group, who will identify known species and describe those that are new to science. “We are collecting on a scale no one has ever attempted, and our results will be unprecedented in the scientific literature,” Amorim says enthusiastically.
Because knowledge gains value when shared, the researchers recently published an article that includes a kind of construction manual for the trap cascade. In the paper, they emphasize that the system can be replicated anywhere in the world, in any forest, to explore insect diversity and dynamics.
