Insects are the largest group of animals on Earth – there are more than 1.4 billion insects per person according to some estimates. Many insects are key pollinators of food crops; the entire existence of human life can be said to hang in the balance of myriad minute six-legged, antennae-wielding exoskeletons.
But 40 per cent of all insect species are at risk of extinction due to land clearing, climate change, introduced pathogens and pesticides. While we ruminate on what this means for the statistical likelihood of our own future, Curtin researchers Associate Professor Paul Nevill and Dr Joshua Kestel are using environmental DNA (eDNA) technology to detect insect species – at a footprint level no less – and their precise pollinating behaviours.
In the latest episode of The Future Of, we speak with Paul Nevill and Joshua Kestel about how this disruptive eDNA tech has the potential to play a crucial role in sustaining important ecosystem services like pollination and, in turn, the food and nature systems on which we rely.
Firstly, Josh, what is eDNA?
Environmental DNA (eDNA) is trace amounts of DNA left from animals in soil, water, air and even on plant material. Using DNA metabarcoding, we can amplify these small little fragments, and we can work out what organisms deposited that DNA – we can literally detect the footprint of a bee.
Once upon a time if you wanted to work out what species had been in a certain area, you had to stand out there like David Attenborough and observe with a camera. But now we can visit a site after organisms have been there and detect entire communities, which is so much more powerful.
Paul, insects may not be ‘charismatic’ creatures, but they are key to a healthy environment. What are the implications of their loss?
The implications are huge. If we just look at the services that insects provide: 85% of wildflowering plants and 75% of agricultural crops are insect pollinated. In fact, insect pollination services contribute $2.6 billion to Australia’s economy.
Insects also perform pest control – dragonflies eat mosquitoes, for example. And decomposition – without beetles we wouldn’t have nutrient cycling. It’s also all the birds and mammals that rely on insects as a food source.
So yes, we should be worried about the loss of insect biodiversity and abundance. It’s kind of like that game Jenga; we can keep stacking up and pulling out the blocks, but at some point there is going to be catastrophic ecosystem collapse. That’s potentially the future if we keep losing our insects.
Josh, your research is ultimately helping to prevent such collapse by showing how eDNA can be used to better detect insect pollinators of key food crops, specifically avocado orchards. Tell us more.
Avocado crops are a big fruit producer in WA that rely on pollination. And with the capabilities of eDNA technology, we were able to expand our research scope to identify the entire insect community that is sustaining avocado orchards in the Southwest region of WA. So not just pollinators, but also pests and predators that interact with these flowers.
And what we found was that the ‘usual suspect’ of avocado pollination, the European honeybee, is not actually that interested in avocado pollen or nectar, yet much of the industry is geared around using honeybees to pollinate avocado flowers.
Our research found that native insects, particularly hover flies, are ferocious visitors of avocado flowers; we detected over 100 visits per hour for this species. Meanwhile, honeybees would avoid avocado flowers and travel up to one kilometre away to native remnant bushland to visit the wildflowers there.
So, it just goes to show there’s a diverse and rich community of native insects that are doing the job of pollination. Although agriculture has traditionally been built around this colonisation idea of bringing our ancestral pollinators with us, we’re actually better off listening to the landscape and utilising what’s there, because clearly there’s amazing insects that are doing the job too. And if we don’t harness them or protect them, we are doing ourselves a disservice.
Josh, tell us more about what your research found about the role of eDNA in pest control?
Farmers currently rely upon their own personal observations of pests to manage them. For example, they might inspect a tree for a species like the six-spotted mite and, if they do detect it, they’ll undertake pesticide spraying of the entire orchard. Now, that would be like one member of your family getting sick and yet giving the whole family antibiotics – it’s overkill.
With eDNA, farmers could conduct targeted pesticide spraying of particular trees that have a pathogen or pest, rather than spray an entire orchard and harm predator diversity, which actually benefits the orchard in the long run.
The next step for this technology is to combine it with the tools currently used in agriculture to make it more accessible to farmers, so eDNA collection can become part of everyday agricultural practice.
Paul, aside from insect pollination, where else can this powerful eDNA technology be applied?
All organisms contain DNA so we can detect any species right across the tree of life, from soil microbial communities to vertebrate species. We can use eDNA in conjunction with traditional monitoring methods, such as cameras, to target a specific species for a conservation outcome. Or, we can use eDNA to look at change within whole communities of organisms, such as the response of insect species to a minesite restoration or the impact of a water pipeline on fish species.
eDNA is an incredibly powerful and disruptive approach that just keeps growing and will have a big role to play in natural capital accounting, and the nature positive market.
Josh, eDNA is such fascinating technology with incredible capabilities. What’s next for your research?
I was fortunate enough to be given a Fellowship to Cambridge University this year; I’ll be doing eDNA sampling in the UK but also South Africa, where I’ll get the chance to look for native pollinators in the desert ecosystem.
It was a surreal moment when I got that phone call about the fellowship, but I can’t wait. Curtin University has given me a wonderful platform to get on the world stage and try something completely new.
Paul, you’re a leading molecular ecologist, but your pathway to this career has been, perhaps fittingly, an organic one?
I wanted to do forestry after high school, but I didn’t actually study science, so I tried a few different things including economics and arts degrees and even worked as an air traffic controller when I was about 20 years old. But I quickly got sick of that and decided to go back to a forestry degree in my early 30s and I’ve never regretted it.
I think most people in our field are not motivated by salaries but the positive impact they can have on biodiversity, and particularly Perth’s biodiversity. We live in an incredible location – we’re in a biodiversity hotspot in Australia – it’s a special place and we must do as much as we can to protect it.
Curious to hear more? Listen to the full episode on The Future Of podcast to explore Josh and Paul’s eDNA research in depth.
