Australian scientists have confirmed the hybridization of two of the world’s major pest species into what they describe as a "new and improved mega-pest." 

Globalisation and increased movement between countries and continents means movement of agricultural pests is becoming more common. 

The scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) said the new hybrid is a combination of the cotton bollworm and the corn earworm.

The cotton bollworm is widespread in Africa, Asia and Europe and causes damage to over 100 crops, including corn, cotton, tomato and soybean.

CSIRO said is "extremely mobile and has developed resistance to all pesticides used against it."

The corn earworm is a native of the Americas and has comparatively limited resistance and host range, they said.

The combination of the two in a "novel hybrid with unlimited geographical boundaries is cause for major concern,", according to the scientists, who say evidence already seen of a clear hybridization of the two moths in Brazil.

"A hybrid such as this could go completely undetected should it invade another country", said CSIRO research director Dr. Paul De Barro

CSIRO said that while a combination of insecticides currently controls these pests well in Australia, it is important to study the pests themselves for sustainable long-term management worldwide.

The scientists confirmed that among the group of caterpillars studied, every individual was a hybrid.

“No two hybrids were the same suggesting a ‘hybrid swarm’ where multiple versions of different hybrids can be present within one population,” said CSIRO scientist Dr Tom Walsh.

The bollworm, commonly found in Australia, attacks more crops and develops much more resistance to pesticides than the earworm.

A concerning finding among the Brazilian hybrids was that one was 51% earworm but included a known resistance gene from the bollworm.

The researchers published their findings in the Proceedings of the National Academy of Sciences of the USA.

Lead author of the paper Dr Craig Anderson, a former CSIRO scientist now based at The University of Edinburgh, believes the hybrid study has wide-ranging implications for the agricultural community across the Americas.

“On top of the impact already felt in South America, recent estimates that 65 per cent of the USA’s agricultural output is at risk of being affected by the bollworm demonstrates that this work has the potential to instigate changes to research priorities that will have direct ramifications for the people of America, through the food on their tables and the clothes on their backs,” Dr Anderson said.

Photo: CSIRO

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