Environmental DNA can help monitor pollinators

Pollinator populations are rapidly declining all around the world, causing a vast variety of plant species to vanish too. In North America, for instance, some pollinator species have fallen by over 95 percent along with many native plants, while in some parts of Europe, wild pollinator diversity has more than halved, and a third of bee, butterfly, and hoverfly species are currently facing extinction. Due to this worrisome global situation, better methods to monitor pollinators are urgently needed. 

Now, a team of scientists led by Curtin University in Australia has examined DNA traces – known as “environmental DNA” (eDNA) – left by animal pollinators on native flora in the Helena and Aurora Range in western Australia, and were surprised to discover traces of not only insect pollinators, as expected, but also mammal and bird ones. While highlighting the benefits of using eDNA to examine the interaction between plants and their pollinators, these findings suggests that the range of pollinators may be larger than previously thought.

“We know the significant role that animal pollinators play in the reproduction of about 90 percent of flowering plants, but this crucial relationship is under threat as many of these species are experiencing declines across the globe,” said study lead author Joshua Newton, a PhD student in Molecular and Life Sciences at Curtin. “That means effective pollinator monitoring methods are now more important than ever before, as we search for new, fast, and accurate ways of safeguarding the future of endangered flora.”

The analysis of eDNA helped scientists identify five mammal species (including the western pygmy possum), eight bird species (including singing honeyeaters and yellow-throated miners), and 57 arthropod species (including several moth species previously unknown to act as pollinators). The native flowers that attracted the greatest diversity of animal visitors were the larger, more generalist species Banksia arborea (commonly known as Yilgarn dryandra) and Grevillea georgeana.

“We were especially pleased to find evidence of a western pygmy possum visiting a flower because at the time it was the first eDNA metabarcoding based identification of an interaction of a mammal or bird species with flowers, to our knowledge,” said study co-author Bill Bateman, a wildlife biologist at Curtin.

“This finding shows us that the eDNA metabarcoding of flowers offers a more complete set of floral visitors and may prove an effective tool for monitoring rare plant species that are growing in remote regions, receive relatively few pollinator visits, or are visited by cryptic animal species.”

The use of eDNA is currently in the early stage of application in terrestrial systems, but soon it may help identifying not only pollinators, but also multiple other species – such as pests or invasive spies – that interact in various ways with plants.

“eDNA offers an opportunity to explore and monitor ecosystems at multiple levels – not just what we are able to easily see, hear, and identify under a microscope,” concluded senior author Paul Nevill, a molecular ecologist at Curtin.

The study is published in the journal Environmental DNA.

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By Andrei Ionescu, Earth.com Staff Writer

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