THE CONFIRMATION of a hybridisation of two moth pest species is being monitored closely by world pest management authorities fearful hybrid pest insect species could quickly develop multiple resistances to insecticides.
Researchers from Australia’s CSIRO made the discovery in Brazil recently that moth species the cotton bollworm (helicoverpa armidera) and the corn earworm (helicoverpa zea) have hybridised.
CSIRO scientist Tom Walsh said at present the hybridisation process was random.
“No two hybrids were the same suggesting a ‘hybrid swarm’ where multiple versions of different hybrids can be present within one population, whatever is possible in terms of crosses could still occur, you could have the majority of the insect armidera or the majority zea, it just depends,” Dr Walsh said.
The two species are destructive pests in a number of crops, primarily summer crops such as corn and cotton, with armidera the most damaging of the two types.
While at present Dr Walsh said Australia had relatively good options in terms of control of helicoverpa in other parts of the world there were multiple resistances to pesticides in particular in the cotton bollworm.
The moths can be an especially big problem in the Americas.
Helicoverpa species are the species targeted in Monsato’s Bollgard cotton technology.
Bollgard varieties make up over 90pc of cotton sown in Australia.
Dr Walsh said the creation of a new hybrid with unlimited geographical range could be a cause for concern.
He said it showed the threat to Australian biosecurity was two-fold, the obvious threat of a new species, such as the incursions of novel pests, like Russian wheat aphid in 2016, and then there is the threat of interbreeding.
“If a new, but closely related, species comes to Australia and breeds with existing populations you run the risk of resistance traits being passed on.”
“We need to think of biosecurity at a genetic, as well as a species level as we can see this hybridisation occurring.”
“In this era of globalisation, we are increasingly going to see related species interbreeding, the spread of insects is much greater with humans moving around everywhere.”
North American agriculture is also watching with concern.
CSIRO’s Craig Anderson said over 65 per cent of the agricultural output of the US would be at risk from impact from the bollworm.