Study reveals how eDNA could bear fruit for farmers and the environment

A Curtin University study has revealed a new method of capturing DNA could provide farmers with a valuable tool for boosting crop production — while also benefiting the environment.

Researchers from the School of Molecular and Life Sciences used an emerging scientific method known as ‘eDNA metabarcoding’, to track which insects interacted with avocado flowers at two orchards in Western Australia.

Led by Dr Joshua Kestel and Associate Professor Paul Nevill, the team took bunches of flowers from avocado trees, which were then frozen and ground up before being taken through the DNA extraction process.

“We use eDNA metabarcoding to effectively amplify the DNA from whatever interacts with that flower and that lets us work out who was there,” Dr Kestel said.

“We are literally able to detect the footprints of a bee.”

eDNA metabarcoding was found to detect five times the number of unique pest species than filming plants with digital cameras, which is another cutting-edge method currently used.

“Digital video recording is advanced, but eDNA metabarcoding is Star Trek level – we are talking about a different universe,” he said.

Dr Kestel said eDNA metabarcoding could help improve yields and make agricultural operations more efficient.

Many farmers hire honeybee hives at significant expense to encourage pollination and grow more fruit, however Dr Kestel said native pollinators aren’t currently part of the bigger picture and their role remains unknown for many types of trees and crops.

“Honeybees aren’t big fans of avocado pollen and nectar: an avocado tree has about a million flowers, but less than 200 will be pollenated and mature into fruit,” Dr Kestel said.

“Using eDNA metabarcoding allows us to detect pollinators, pests, and — quite conveniently — predator species which can help protect crops by eating these pests.”

Dr Kestel said there was immense benefit to knowing which pests were occurring in a crop or orchard and where on the trees they were.

He said it would give farmers the option to introduce natural predators or, if they were to use pesticides, to use them more efficiently and in a more targeted way.

“At the moment we manage these pests with very generalised methods, which comes at a huge cost as the pesticides kill the wild pollinators and the natural predators, not just the pests you want to be rid of.

Dr Kestel said while the application of eDNA metabarcoding was still in its infancy, it could have a large impact.

“While it's not yet widely adopted, there's growing interest in this technology because there's a recognition of how powerful it is.”

‘Spatio-temporal variation in arthropod-plant interactions: A direct comparison of eDNA metabarcoding of tree crop flowers and digital video recordings’ was published in Ecological Indicators.