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Stalls Everglades Invader
By Alfredo Flores
November 7, 2002
For years, melaleuca--a fast-growing
invasive tree from Australia--has been taking over 14 to 15 acres a day of
south Florida's Everglades, making it a significant threat to the stability of
this fragile ecosystem.
Now, to the rescue has come a gnat-sized psyllid, Boreioglycaspis
melaleucae. This tiny insect is a natural enemy of melaleuca in its native
country, and both adults and their offspring feed on the tree's clear sap.
Their favorite sap is inside the tips of a melaleuca's newest stems and
branches. Young melaleuca seedlings are the most vulnerable to the psyllids'
attack, but the pests can also stunt the growth of bigger trees. Their feeding
slows down melaleuca seed production by damaging tips that would otherwise form
Some 100,000 psyllids have been released at a variety of south Florida
sites, ranging from a cluster of melaleuca trees standing in water to an
unusually dry pasture dotted with melaleuca stumps. The psyllids' presence in
south Florida is the result of more than five years of research by
Agricultural Research Service scientists
at the Australian
Biological Control Laboratory in Indooroopilly, Australia, near Brisbane;
their colleagues with Australia's Commonwealth
Scientific and Industrial Research Organization; and co-investigators at
the ARS Invasive
Plant Research Laboratory, headquartered in Fort Lauderdale, Fla., with a
satellite location in Gainesville, Fla.
Philip W. Tipping, an ARS entomologist at the Fort Lauderdale lab, and
colleagues expect the psyllid to complement the efforts of another weed warrior
from Australia--the melaleuca leaf weevil, Oxyops vitiosa. Its first
release was made in 1997, with 1,600 weevils distributed at 11
melaleuca-infested sites in south Florida. Today, millions of the
quarter-inch-long weevils are eating the silvery leaves of melaleuca saplings.
Losing leaves stresses the trees and lowers seed production, which can
otherwise reach 60 million seeds a year in mature trees.
More about research on these two melaleuca-controlling insects can be found
in the November issue
of Agricultural Research.
ARS is the U.S. Department of
Agriculture's main scientific research agency.