There's an innovative eDrone that collects environmental DNA in trees

Developed in Switzerland by ETH, WSL and Spygen the flying robot that lands on even the most difficult branches to take biological samples

eDrone: The eDrone approaches a branch for sampling environmental DNA
The eDrone approaches a branch for environmental DNA sampling (Photo: Gottardo Pestalozzi/WSL)

The researchers of Federal Polytechnic of Zurich and Federal Institute for Forest, Snow and Landscape Research they have developed a flying device that can land on tree branches to take samples.
This opens up a new dimension of study for scientists, which until now was reserved for the most daring climbers.

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eDrone: the number 1 eDNA operation infographic for eDNA research by ETH and WSL
The number 1 infographic of the biodiversity survey made with a flying robot for the collection of eDNA. The eDrone is remote controlled over a previously identified branch; autonomously lands on it and establishes stable contact to collect the eDNA; After sampling, the eDrone can be remote-controlled to the base station and samples can be retrieved, stored and shipped to the designated laboratory for eDNA analysis. The eDNA is extracted, amplified with universal primers and sequenced. The results are generated by comparing the sampled environmental sequences with a species identification database. The illustration describes how the collected species (their class and family) were identified from the 14 samples collected with the eDrone in this proof-of-concept or proof-of-feasibility study. For each species, the number of DNA readings (Nb) as well as the sampling method that identified it are reported
(Illustration: WSL Environmental Robotics Laboratory)

eDNA, or “environmental DNA”, is the genetic material in the environment

Ecologists increasingly use traces of genetic material left by living organisms in the environment, called environmental DNA (eDNA, for "environmental DNA"), to catalog and monitor biodiversity.
Based on these DNA traces, researchers can determine which species are present in a certain area.
Obtaining samples from water or soil is easy, but other habitats, such as forest canopies, are difficult to access.
As a result, many species remain untraced in poorly explored areas.
The researchers ofETH Zurich, the WSL and the company Spygen of Le Bourget-du-Lac, France have teamed up to develop a drone that can autonomously collect samples on tree branches.
The institution is a research institute of the Swiss Confederation, is part of the Federal Polytechnic Sector and employs around 500 people.
In addition to its main offices in Birmensdorf (Zurich) and Davos (WSL Institute for the study of Snow and Avalanches, acronym SLF, in Grisons), it also boasts a regional presence in Lausanne (Vaud), Cadenazzo (Ticino) and Sion (Valais).

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eDrone: The sticky surface of the eDrone touches a branch to collect eDNA
The adhesive surface of the eDrone touches a branch to collect eDNA (Photo: Gottardo Pestalozzi/WSL)

Adhesive strips for collecting samples, paying attention to the support

The drone is equipped with adhesive strips. When the aircraft lands on a branch, the branch material sticks to these strips.
Researchers can then extract the DNA in the laboratory, analyze it and assign it to the genetic matches of various organisms using comparative data available in scientific databases.
But not all branches are the same: they vary in terms of thickness and elasticity. Also, the branches bend and bounce when a drone lands on them.
Programming the aircraft to autonomously approach a branch and remain stable on it long enough to take samples was a challenge for the engineers.
“Landing on branches requires complex control”, explains Stefano Mintchev, Professor of Environmental Robotics at the ETH Zurich and at the Federal Research Institute for Forest, Snow and Landscape.
Initially, the drone doesn't know how flexible a branch is, so the researchers fitted it with a cage capable of sensing the force exerted.
The drone measures this factor and takes it into account for its flight maneuver.

There is a drone that "climbs" trees to protect them

eDrone: the number 2 eDNA operation infographic for eDNA research by ETH and WSL
The number 2 infographic of the biodiversity survey made with a flying robot for the collection of eDNA. The eDrone is remote controlled over a previously identified branch; autonomously lands on it and establishes stable contact to collect the eDNA; After sampling, the eDrone can be remote-controlled to the base station and samples can be retrieved, stored and shipped to the designated laboratory for eDNA analysis. The eDNA is extracted, amplified with universal primers and sequenced. The results are generated by comparing the sampled environmental sequences with a species identification database. The illustration describes how the collected species (their class and family) were identified from the 14 samples collected with the eDrone in this proof-of-concept or proof-of-feasibility study. For each species, the number of DNA readings (Nb) as well as the sampling method that identified it are reported
(Illustration: WSL Environmental Robotics Laboratory)

Preparation with 21 types of organisms in the forest of… Zurich Zoo

The researchers tested their new device on seven tree species.
In the samples they found DNA from 21 distinct groups of organisms, or taxa, including birds, mammals and insects.
“It is an encouraging figure, because it shows that the collection technique works”says Mintchev, co-author of the study just published in the journal Science Robotics.
The researchers now want to further improve their drone to prepare it for a competition in which the goal is to locate as many different species as possible in 100 hectares of rainforest in Singapore in 24 hours.
To test the drone's efficiency under conditions similar to those it will experience at the competition, Mintchev and his team are currently working in the Masoala rainforest at Zurich Zoo.
“Here we have the advantage of knowing which species are present, which will help us better assess how accurate we are in collecting eDNA traces with this technique or if we are missing something.”, says Mintchev.

Captured in Valais… the invisible stress of a forest

eDrone: scholars Emanuele Aucone and Christian Geckeler at work on the eDrone
Scholars Emanuele Aucone and Christian Geckeler at work on the eDrone (Photo: Gottardo Pestalozzi/WSL)

Challenge in Singapore: 10 times more plants in one day

For this event, however, the harvesting device needs to become more efficient and move faster.
In tests conducted in Switzerland, the drone harvested material from seven trees in three days; in Singapore, it must be able to fly and collect samples from ten times as many trees in a single day.
Collecting samples in a natural rainforest, however, presents researchers with even greater challenges.
Frequent rains wash eDNA off surfaces, while wind and clouds prevent drones from functioning.
“We are therefore very curious to see if our sampling method will also prove itself in extreme conditions in the tropics”, says Mintchev.

Video, the stress of a Swiss forest detected by drones

The Swiss eDrone to collect environmental DNA filmed in multiple situations

The Swiss eDrone to collect environmental DNA filmed during indoor tests

The Swiss eDrone to collect environmental DNA filmed from below on landing

The Swiss eDrone for collecting environmental DNA filmed sideways in action

The Swiss eDrone to collect environmental DNA filmed from the side of the landing

eDrone: The eDrone in contact with a branch to collect surface eDNA
The eDron in contact with a branch to collect surface eDNA (Photo: Gottardo Pestalozzi/WSL)