Insect pollinators are just as important for native flowers as they are for crops. We’re unveiling the hidden pollinator networks in the Australian alps.
A field of wildflowers in the spring is a bustling community of flowering plants and insect pollinators. They depend on each other for survival. But their interactions also form a complex network with an important role in how the ecosystem functions.
We’ve been studying alpine pollinator networks and how environmental factors shape them. And we’re using insects to do the fieldwork with us.
Tiny, expert botanists
Imagine if you could ask an insect what plants it has visited. It would be faster and cheaper than sending researchers into the field to observe flowers and record which insect species visit them.
“Insect pollinators are experts at surveying flowering plants. They carry traces of pollen from each flower they visit,” Liz said.
“We can extract DNA from the pollen insects carry and use it to identify the plant species they visited. This can reveal two things: what species are flowering in the area and which insect species pollinate which plant species.”
This new technology is called pollen DNA metabarcoding. It means researchers can build pollinator networks that show the relationships between the insect species and flowering plant species present in an area. But Liz noted there are some things that a fly or a bee just can’t do in the field.
“People have the added advantage of being able to identify plants that are non-flowering or not currently flowering. People can also map plant locations and count how many are present, which is important for conserving threatened species,” she said.
Pollinator networks in the alps
Our pollination researchers spent a week on a field trip at Charlotte Pass in Kosciuszko National Park during December 2017. They set up 12 study plots between 1800 and 1946 metres above sea level in three different habitats: alpine herbfield, subalpine woodland and alpine heath.
“Insect pollinators from many different groups visit alpine flowers, including bees, butterflies, beetles and flies,” Francisco said.
“During our fieldwork, we observed insects visiting flowers and we also collected 154 insect specimens for pollen DNA metabarcoding. Back in the lab, we compared pollinator networks using both approaches, human observers versus pollen DNA metabarcoding.
“We expected the networks built using pollen DNA metabarcoding to be more diverse than observation networks. And this is what we found. Pollen DNA metabarcoding also detected many cryptic plant species that we didn’t know were present.
“Overall, we found that alpine pollination networks are very generalised and are influenced by habitat and microclimate,” he said.
The study found that the large diversity or mosaic of alpine habitats, including heath, subalpine woodland and herbfields, plays a crucial role in maintaining the cohesiveness of alpine plant-pollinator communities.
“This has further implications to understand the impact of climate change. The potential shrinking or disappearance of this diversity of alpine habitats or microhabitats could trigger the extinction of many native plant and insect species,” Francisco said.
“Our research studying the impacts of climate change in the Australian Alps will help us improve the conservation and management of this threatened ecosystem.”
Other research by pollinators
Pollen DNA metabarcoding depends on the science of taxonomy. Entomologists identify the insect pollinators. Then the DNA of the pollen they carry is compared to reference DNA sequences that were generated using expertly identified plant specimens.
The technology is useful in many different ways. We could deploy bees to monitor vegetation and detect weeds in remote areas or after bushfires. We could study the behaviour of different species of pollinators or measure pollinator services to agriculture. We’ve already used it to test which location honey comes from.
And we can look back in time. Many insect specimens in our Australian National Insect Collection still have pollen stuck to their bodies, even if they were collected decades ago. We plan to take pollen from historical specimens to find out how pollinator communities have changed through time due to changes in land management and climate. This will help us predict the future of pollination services for native plants, agriculture and horticulture.