Scientists have traced the origins of a very hungry caterpillar in efforts to halt the spread of the diamondback moth, a pernicious, pesticide-resistant pest costing the world's farmers more than $5 billion per year.
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A study published in Nature Communications has analysed the genetic makeup of more than 530 diamondback moths collected from across the world.
Researcher Geoff Gurr, professor in applied ecology at Charles Sturt University, says for years scientists had been "barking up the wrong tree," with theories the moth came from the Mediterranean or China.
The first insect to adapt to DDT - the toxic 1950s poison of choice banned in Australia since 1987 - the moth is a common pest in vegetable gardens and farms.
It is resistant to all major classes of insecticide, making control difficult.
Professor Gurr, of NSW's Graham Centre for Agricultural Innovation, says caterpillars feed on brassica crops, like cabbage and canola, and cost more than $5 billion world-wide in production loss and pest control.
By documenting the full genomes of moths from 114 locations across 55 countries, scientists were able to learn where the moth came from and how it spread to become one of the planet's most serious pests.
"The diamondback moth originated in South America, and started moving about 500 years ago, initially through Central and North America before invading Europe, Asia and finally the Pacific," Prof Gurr said.
Most of their travel was accidental, he added, via unsuspecting European colonists and traders who were transporting commodities across the oceans.
The diamondback moth used its ability to adapt to cope with the new climates and foods, fuelling a population boom.
"Genetically speaking, Australia has a 'young' population of diamondback moth but even here it has adapted to feeding on native, brassica weeds as well as important crops," Prof Gurr said.
Now researchers know where the moth came from they can focus on finding a natural predator or parasite to help control it, he added.
Funded by the Chinese government and led by researchers from Fujian Agriculture and Forestry University, the expensive study illustrated how serious the pest is to global food security, Prof Gurr said.
"And how badly we need to lift our game and find better control options."
Australian Associated Press
