They are developing a special drone to collect samples from tree branches

They are developing a special drone to collect samples from tree branches

Ecologists are increasingly using traces of genetic material left in the environment by living organisms, called environmental DNA (eDNA), to catalog and monitor biodiversity and determine which species occur in a selected area.

Obtaining samples from water or soil is easy, but other habitats, such as the canopy of trees, are difficult for researchers to access, meaning many species in understudied areas go unmonitored.

That’s why scientists from ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, together with the company SPYGEN, have developed this drone, which is equipped with adhesive strips to which the material of the branches sticks when the plane lands on it.

This makes it possible for experts to extract DNA in the laboratory, analyze it and assign it to genetic similarities in the various organisms by comparing databases.

However, landing on the branches requires complex controls, explains Stefano Mintchev, Professor of Environmental Robotics at ETH Zurich and WSL.

Since the drone does not initially know how flexible a branch is, the researchers equipped it with a force-measuring cage that enables it to measure this factor on site and include it in its flight maneuvers.

During home tests in Switzerland, the drone collected material from seven tree species over three days and found DNA from 21 different groups of organisms, including birds, mammals and insects.

“This is encouraging because it shows that the collection technique is working,” Mintchev said.

However, collecting samples in a natural rainforest poses even more difficult challenges for researchers, as frequent rain washes eDNA from surfaces, while wind and clouds hamper the drone’s operations.

“We are therefore very curious to see whether our sampling method will also be tested under extreme conditions in the tropics,” says the co-author of the study.