Stop the aliens invading says biologist

Professor Andrew Lowe.
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Monday, 6 April 2009

A University of Adelaide biologist is calling for a tightening of the importation of foreign plant material into Australia to stop the spread of super weeds, which cause $4 billion damage to agriculture and the environment each year.

Professor Andrew Lowe from the University's Australian Centre for Evolutionary Biology and Biodiversity says quarantine restrictions need to be stricter to halt the importation of foreign species that are already established, or known problem weeds in Australia.

"Our research shows that in most cases super weeds become a problem after multiple introductions from different sources. By combining this genetic variation, new genetic mutations can arise that can give the alien species the potential to adapt and turn super-invasive," Professor Lowe says.

"These human-mediated modes of introduction, which are very different to the way that plants naturally colonise new ranges, appear to be the root of the problem. In light of these findings, we should be changing our species introduction practices nationally and globally to severely limit the importation of new genetic material for plant species that have been identified as established or weedy."

Professor Lowe says many of the most potent weeds were originally introduced for horticulture or as crops and so variations in stock characteristics, like flower colour, were positively encouraged.

A typical example is Fireweed, a yellow flowering weed that was introduced into the Hunter Valley in 1918 from South Africa. The plant is now found right across eastern Australian farming systems and is poisonous to livestock.

Scotch Broom is another example of a noxious weed which has had multiple introductions from Eurasia, infesting both grazing lands as well as natural ecosystems.

Professor Lowe says of 2700 introduced plant species to Australia, 429 are now regarded as a major problem.

"In some cases we can introduce bio-control agents (such as moths for the prickly pear) to keep infestations at bay, but this is not always possible"

Professor Lowe's findings were recently published in the international scientific journals Trends in Ecology & Evolution and Trends in Plant Science.

They are the product of a three-year, $560,000 Australian Research Council grant and research partnership involving PhD student Elly Dormontt and Dr Peter Prentis, from the University of Adelaide, in collaboration with South African scientists Professor Dave Richardson and Dr John Wilson from Stellenbosch University.

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