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Photo: Australian pine trees.
Researchers are working on DNA fingerprints so they can accurately identify lookalike species and subspecies of invasive Australian pines. Photo courtesy of Amy Ferriter, South Florida Water Management District,

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Scientists Sort Out “Who's Who” Among Australian Pine Species

By Marcia Wood
October 24, 2008

Invasive Australian pines that crowd out native plants in Florida present a particular conundrum. In the Sunshine State, it can be very difficult to tell the look-alike Casuarina species and subspecies from one another.

Correct identification is important to the Agricultural Research Service (ARS) scientists who want to import Casuarina-quelling insects from the invasive tree's Australian homeland to stop the plants' uncontrolled advance in Florida. But until they know who’s who among the confusing Casuarina trees, researchers won’t be able to precisely match the helpful insects with the exact Casuarina with which they evolved in Australia. Perfect matches may be critical to the insects’ success in the United States.

To solve the identity puzzle, ARS botanist and research leader John Gaskin is analyzing DNA taken from Casuarina trees growing in Australia, where their identification is certain. He’s comparing that to DNA from the Casuarina trees currently running amok in south Florida.

Technicians Kim Mann and Jeannie Lassey, who work with Gaskin in the ARS Pest Management Research Unit in Sidney, Mont., extract DNA from leaves that Gaskin collected in 2006 from Casuarina treesgrowing along Australia’s eastern coast.

They’re also working with Casuarina specimens gathered elsewhere in Australia by four co-investigators: Matthew Purcell and Bradley Brown of the ARS Australian Biological Control Laboratory in Indooroopilly, Australia; Gary Taylor of the University of Adelaide in Australia, and Greg Wheeler of the ARS Invasive Plant Research Laboratory in Ft. Lauderdale, Fla.

The study is the first to use DNA to definitively identify Casuarina trees in Florida. Gaskin expects to have final results sometime this year.

ARS is a scientific research agency of the U.S. Department of Agriculture.