CANBERRA, April 6 (Xinhua) -- Australian scientists have confirmed that two major caterpillar pest species' have hybridized into a ravenous mega-pest.

Researchers from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have found evidence that the cotton bollworm and corn earworm have created a new species that is likely to be resistant to pesticides.

The cotton bollworm is found in Africa, Asia and Europe where it causes damage to over 100 crops while the corn earworm is native to the Americas.

It is estimated that the damage caused by the two worms costs farmers around the world eight billion Australian dollars (6.1 billion U.S. dollars) annually in lost production and control measures.

The combination of the two has been described by the CSIRO as cause for major concern.

"A hybrid such as this could go completely undetected should it invade another country. It is critical that we look beyond our own backyard to help fortify Australia's defense and response to biosecurity threats," Paul De Barro, Research Director of the CSIRO's Biosecurity Risk Evaluation Program, said in a media release on Friday.

CSIRO researchers studied a group of hybrids found in Brazil, finding that multiple versions of different hybrids were present within the one population.

One of the hybrids studied was 51 percent earworm but had a familiar resistance gene found in the bollworm.

Craig Anderson, lead author of the study, said the concern was most pressing in the Americas.

"On top of the impact already felt in South America, recent estimates that 65 percent of the USA's agricultural output is at risk of being affected by the bollworm," he said.