Pest hits Maui papayas
By Kevin Dayton
Advertiser Big Island Bureau
HILO, Hawai'i — A papaya mealybug that poses a new threat to crops in Hawai'i has been discovered on two University of Hawai'i plots on Maui, and experts warn it could easily expand its territory to other islands.
Mach Fukuda • HawaiÎi Department of Agriculture
Testing is still being done to determine how far the pest has spread, but the mealybug infestation may extend from Kahului to Kihei, an area so large that eradicating the pest may be impossible, said Mach Fukada, Maui entomologist for the state Department of Agriculture.
The papaya mealybug has 60 plant hosts, including papaya, avocado, hibiscus and plumeria.
That is bad news for Hawai'i farmers, since the papaya mealybug has 60 plant hosts, ranging from papaya and avocado to hibiscus and plumeria.
The bug drinks the sap from plant stems and injects a toxin, causing stunted growth, deformed leaves, early fruit drop and plant death, according to a warning issued yesterday by the state Department of Agriculture.
"I was reading it and I was telling myself that it will be a disaster to agriculture on the Big Island, considering that papaya mealybug has a lot of host plants," said Emerson Llantero, general manager of the Puna-Hawai'i King Papaya Cooperative.
Hawai'i farms have been hit repeatedly with imported pests and diseases, he said. Examples include the blackspot fungus, white peach scale and the devastating ringspot virus that nearly destroyed the papaya industry in the early 1990s, as well as the bunchy top virus that now threatens the banana industry.
Llantero said federal authorities impose strict safeguards to protect Mainland farms from fruit flies and other pests that could be imported from Hawai'i, requiring federal inspections and expensive treatments of many Hawai'i crops, including papaya.
"I think it is about time that Hawai'i demands reciprocal protection," he said.
The papaya mealybug, known by the scientific name Paracoccus marginatus, was discovered in UH College of Tropical Agriculture and Human Resources papaya trees in an urban garden at Maui Community College and at a test plot off Hansen Road near the Pu'unene Mill, Fukada said.
Mainland tests confirming the identity of the pest were completed June 2, and more tests are pending to confirm other suspected papaya mealybugs found in Kihei. Insects believed to be papaya mealybugs also were taken from hibiscus and plumeria plants from the same areas and are awaiting testing, Fukada said.
Papaya mealybug females are yellow with a white waxy coating, and grow to about one-sixteenth of an inch long. The males are smaller, and infestations look like clusters of cotton-like masses on leaves and stems.
The papaya mealybug is native to Mexico and Central America, and since the mid-1990s has been reported in the Caribbean Islands, Florida, Puerto Rico and South America. Heavy infestations were also found on Guam in 2002 and on Palau last year, according to the Department of Agriculture.
Fukada said plants with papaya mealybug could have been imported from Florida or Guam, but authorities will probably never know exactly how the bug arrived in Hawai'i.
Preventing the spread between the islands may be possible, but Fukada said the risk is that people will take infested fruit or plants on interisland trips.
That means farmers in other parts of the state have very real cause for concern, he said. If farmers are vigilant and aggressively attack any appearance of the bugs with pesticides, "I'm sure it can be managed," Fukada said. "It's going to be one more thing they have to watch out for."
The Board of Agriculture theoretically could order a quarantine, but because the bug uses 60 plants for hosts, enforcing the quarantine would be difficult, he said.
Janelle Saneishi, public information officer for the department, said agriculture officials need to study the problem before making any decision on quarantine.
"It's always a possible option in a case like this, but whether it's feasible and practical, we need to determine," she said.
Programs on the Mainland have discovered parasites that were successful in controlling the papaya mealybug, and the state Department of Agriculture will work with its federal counterpart to determine if the same parasites can be imported to Hawai'i without affecting native insects.
Maui residents who suspect their plants have the mealybug should call the state agriculture office on Maui at (808) 873-3555. On other islands, call the nearest state agriculture office or the Plant Pest Control Branch in Honolulu at 973-9522.
Reach Kevin Dayton at (808) 935-3916 or kdayton@honoluluadvertiser.com.
