A blog maintained by Tevita Kete, PGR Officer
Secretariat of the Pacific Community (SPC), Suva, Fiji Islands
This weblog documents the activities of Pacific Agricultural Genetic Resources Network (PAPGREN), along with other information on plant genetic resources (PGR) in the Pacific.
The myriad varieties found within cultivated plants are fundamental to the present and future productivity of agriculture. PAPGREN, which is coordinated by the Land Resources Division of the Secretariat of the Pacific Community (SPC), helps Pacific countries and territories to conserve their crop genetic diversity sustainably, with technical assistance from the Bioversity International (BI) and support from NZAID and ACIAR.
SPC also hosts the Centre of Pacific Crops and Trees (CEPaCT). The CEPaCT maintains regional in vitro collections of crops important to the Pacific and carries out research on tissue culture technology. The CEPaCT Adviser is Dr Mary Taylor (MaryT@spc.int), the CEPaCT Curator is Ms Valerie Tuia (ValerieT@spc.int).
PAPGREN coordination and support
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Tuesday, August 05, 2003
Posted 2:37 PM by Luigi
Papaya in Guam
By Katie Worth
A year ago, it looked like Guam residents might not be able to make that offer much longer, as the island's papaya crops were being razed by an imported killer three millimeters long -- the papaya mealybug.
Fortunately, however, scientists have come to the rescue and Guam's papaya crops are now growing their way back to health.
In June of 2002, Rangaswamy Muniappan of the University of Guam's Agricultural Experiment Station, with the help of biological control specialists from the U.S. Department of Agriculture, began releasing three species of microscopic, stingless wasps imported from Puerto Rico to combat the destructive papaya mealybugs.
According to Muniappan, the parasitic wasp seeks out a mealybug and deposits an egg inside of it. The egg then grows into a larva, and essentially eats the mealybug from the inside out, thereby killing it, he said.
"It's been very, very successful," said USDA biological control specialist Dale Meyerdirk, noting that at sites they've been monitoring for the last year, papaya mealybug populations have dropped by more than 95 percent.
Farmer Bernard Watson, who said his papaya crop was destroyed by the bugs before the parasites were released, corroborated the data.
"The parasites have done an excellent job at controlling the (mealybug) population," Watson said. "Before they started releasing them, ... it was pretty bad. It almost brought a lot of people's productions to a halt."
The papaya mealybug originated in Mexico, Meyerdirk explained, and at some point jumped to islands in the Caribbean. When those islands' papaya crops were wiped out, scientists went to Mexico to find the natural enemy of the pests.
Scientists found the parasites that kill the Papaya mealybugs, and after sending them to a facility in Delaware for extensive research into any possible negative environmental consequences, they introduced them to the Caribbean islands, and later to the U.S. mainland, which the bug later infested. Those programs were successful, Meyerdirk said.
So when the papaya-killing bug found its way to Guam, probably by hitchhiking on some imported fruits, the obvious solution was to import the parasites as well, Meyerdirk said.
The papaya mealybug has spread from Guam to Palau, Muniappan said, adding that he, Meyerdirk and USDA entomologist Richard Warkentin flew to Palau last weekend to establish a similar biological control program there. Muniappan said the bug had not yet been reported on Hawaii or other Pacific islands.
The bug has an impact on many species of plants, Muniappan said, including hibiscus and the ubiquitous plumeria. He said the bugs' saliva is toxic to the plants, so when the bugs pierce the plants to suck out the sap, they poison them.
The parasites shouldn't present a problem to the island, Meyerdirk said, because their population decreases as the mealybug's population decreases.
"But the parasite will never totally eliminate its host because if it did that it would die out," he said.
There are other species of mealybugs, including the pink hibiscus mealybug, that also plague Guam. Similar biological controls exist for those bugs, but so far they haven't been implemented because they affect mostly ornamental plants, therefore, there is less pressure to fund those projects.
But at least the papaya mealybugs are no longer a scourge to the island, Muniappan said.
"Right now this problem on Guam is solved, and it didn't cost the farmers anything," Muniappan said. "They are satisfied because last year at this time they couldn't plant papaya."
The island's farmers are again growing papayas, now that an introduced species of papaya-killing mealybug has been mitigated by another introduced insect.
Pacific Daily News: www.guampdn.com
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