Scientists trace origin of one of agriculture’s worst pests

By Rodney Woods

A Charles Sturt University scientist has contributed to landmark research tracing the origin and historical patterns of spread for one of agriculture’s worst pests — the diamondback moth.

The study, by an international team of scientists and published in Nature Communications, analysed the full genomes of more than 530 diamondback moths collected from 114 locations across 55 countries.

Charles Sturt University Professor of Applied Ecology Geoff Gurr, who is also from the Graham Centre for Agricultural Innovation and School of Agricultural and Wine Sciences, said the diamondback moth was a common pest in vegetable gardens and farms.

“Caterpillars feed on brassica crops, like cabbage and canola, costing more than $5 billion worldwide in lost production and control costs,” Prof Gurr said.

“Diamondback moth is also extremely adept at developing resistance to pesticides, which makes chemical control difficult.”

Prof Gurr said the latest research had provided scientists with new insight into the biology of the moth to find out where it came from and how it had spread to become one of the planet’s most serious pests.

“We have discovered 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,” he said.

“Most of this movement was accidental by human activities, European colonists and traders, transporting commodities across oceans.

“Along the way, the diamondback moth used its adaptive capacity to cope with the new climates and plants it encountered.

“Of course, the global expansion of agriculture, including the brassica plants it specialises in, fuelled growth of populations sizes.”

Proff Gurr said 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.

“This finding that the pest originates in South America is a major breakthrough because all previous theories about its origin, such as the Mediterranean or even in China, had us barking up the wrong tree,” he said.

“Now that we know where the diamondback moth originally came from we can focus our energy on looking in the right place for better natural predators and parasites to help give us control of this devastating pest.”