Pesky White Peach Scale Targeted in Tropical
By Marcia Wood
July 17, 2009
aloha spirit isnt really meant for the white peach scale.
This troublesome insect attacks not only its namesakepeachesbut
also many other crops, including Hawaiis famed papaya trees.
Known to scientists as Pseudaulacapsis pentagona, the scale first
showed up in Hawaii in 1997. To stop its spread,
Agricultural Research Service (ARS)
scientists in Hawaii are investigating the use of a tiny wasp to attack and
kill the scale. ARS research entomologists
Hollingsworth and University of Hawaii
postdoctoral researcher Gabor Neumann are collaborating in the work.
Theyre based at the ARS
Pacific Basin Agricultural Research Center in Hilo, Hawaii.
The adult scale is about one-eighth-inch long, and is referred to as
armored because of its protective shell. But the armor doesnt
stop the wasp, called Encarsia diasapidicola. The female wasp, which is
many times smaller than the scale, can slip an egg under the armor and into the
scale. The egg hatches into a nearly microscopic, worm-like larva that slowly
kills the scale by feeding on its innards.
In laboratory tests, the scientists have shown that the wasp, which is
harmless to people, pets and livestock, also doesn't pose a threat to
"nontarget" scales. Those nontargets include the palm
scalenative to Hawaiiand the false oleander scale.
The scientists must have this evidence in order to win government
permissions to turn the helpful wasp loose in Hawaii.
The idea of using the wasp to kill the scale isnt new, but the Hawaii
team is the first to investigate this science-based strategy to control the
scale in The Island State.
more about this research in the July 2009 issue of Agricultural
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.