The 2018 TEDxBrisbane, held on Sunday, is now part of an internationally recognised network of ideas aiming to transform traditional thinking on problems.

These were only two ideas where science was centre stage and the day's talks were streamed to 15 million people worldwide from the city's newest conference venue, the revamped Howard Smith Wharves.

A third scientist, Brisbane koala ecologist Dr Grant Hamilton, surprised the crowd by telling them even the best koala spotter missed 25 per cent of koalas and that commonly the "well-intentioned, but non-expert observers" found only 25 to 30 per cent of the koalas in the area.

"Stop and think about this for a moment and you will realise that critical decisions about habitat preservation, conservation funding, land development approvals are probably being made based on koala population survey data where they only saw 25 per cent of the koalas that are actually there.

'There had to be a better way."

Dr Hamilton explained his team's combination of heat-sensing cameras loaded onto drones that recorded data which could 100 per cent identify koalas in the trees, reported in October by the Brisbane Times.

But the loudest applause came for toadbuster scientist Rob Capon, who explained his scheme to develop a cane toad "smoothie" to attract cane toad tadpoles to eat the cane toad eggs and drive the cane toad population backwards.

Even some crocodiles and snakes die when they eat cane toads.

Professor Capon stood beneath an giant image of bulging-mouthed bufo marinus, introduced into north Queensland in 1935 to control beetles in Queensland's sugar cane industry.

Just 100 adult cane toads were bought to Australia from South America. There are now hundreds of millions of poisonous toads in Australia.

"Cane toads reproduce at an astonishing rate and they've eaten just about everything and they are  highly poisonous across all life stages," Professor Capon said.

"In 2010 Time magazine placed the cane toad in the top three invasive species in the world."

So Professor Capon developed an idea to turn the poisonous cane toad on itself.

His team has developed a way to attract cane toad tadpoles back to the cane toad eggs in the streams and ponds and get them to eat their own eggs.

Professor Capon received warm laughter when he referred to Chinese general Sun Tzu who 2500 years ago wrote, "The supreme art of war is to subdue the enemy without ever fighting."

Ecologists had observed that cane toad tadpoles would eat cane toad eggs even in the dark.

They are lured by the smell.

"We discovered that toad tadpoles are drawn to a chemical attractant, which are released by toad eggs," he said.

"This was a eureka moment. We knew we could extract the attractant from dead adult toads.  But we would need a whole lot of dead toads.'

They received thousands of dead toads and literally blended them together.

"It was an approach which was part CSI, part Survivor and part Mythbusters," he said.

"Put simply we used a giant stainless steel blender to make toad smoothies to get large amounts of toad attractant."

This toad-attractant material is placed in a simple plastic funnel trap near a swarm of cane toad tadpoles.

"The theory worked. When the traps were placed in the shallows, where tadpoles congregate, a single bufo trap in a funnel attracted and trapped several thousand poisonous toad tadpoles in a  couple of minutes."

A not-for-profit organisation now provides the baits and teaches the public how to use them.

"It is early days but our tadpole trappers have already removed more than a million poisonous toad tadpoles from local waterways."

On a more traditional science approach, QUT's Trudi Collet described how she and her QUT Indigenous Medicine Group found a cure for the four different strains of the deadly dengue virus with an extract from a native Australian plant.

The mosquito-borne virus is common in Africa, Asia, South America and some parts of northern Queensland.  Estimates suggest about 100 million cases occur each year and up to 20,000 deaths each year.

"We have 100 per cent been able to kill and clear all four types of the dengue virus," Dr Collet said to warm applause from more than 600 people sitting in Howard's Hall.

"It has never been done before."

Afterwards, Dr Collet explained her thinking about the dengue virus, which causes severe fever, vomiting and joint pain.

"My research focuses on Australian native plants and last year (when Dr Collet also delivered a TEDx talk) you could not turn the television or turn the radio on without hearing something about Zika virus," she said.

Zika virus is a similar mosquito-borne virus, which strikes children and is harmful to pregnant women.

"So I just had a gut feeling that it (my native plant extract) was going to work and it would be able to kill the Zika virus," she said.

At that point the QUT researchers were trying to tackle disease-causing bacteria. Dr Collet switched focus to tackling viruses.

"So I tested our plant extract against the Zika virus and it was absolutely mind-blowing because we realised that we could totally eliminate the virus without damaging the (primate) cells that we were using.

"So the virus is killed and the cells are still strong and healthy. No problem."

The Australian native plant cannot be identified because it is now intellectual property.

Dr Collet believes in three years people will be able to swallow a tablet to prevent them catching dengue fever and it will also be a preventative to the virus.

"It will be a tablet form and we are hoping it will be within three to five years," she said.

Dr Collet reminded the audience that the research and the cure came from Brisbane.

"At the heart of this achievement will be an Australian native plant," she said.

"Perhaps the next time you look at an Australian native plant you might wish to consider what power is hidden within," she told the audience.

TED conferences began in Monterey, California, in 1984, and have been held in Brisbane since 2012, first as TEDxSouth Bank, now TEDxBrisbane.

It is now a worldwide discussion forum where the flagship conferences are held each year in a city on North America's west coast on arts, science, education, innovation, technology and the environment.

Brisbane Times is a sponsor of TEDx 2018.