Papaya Mealybug [Paracoccus marginatus Williams and Granara de Willink].  The papaya mealybug (PM) was discovered on Oahu for the first time in September 2005 at Laie near the northernmost point of the island. Infestations were observed on papaya and hibiscus plantings. It was learned that the mealybugs were very likely introduced there from a nursery in Waimanalo that provided the hibiscus plants purchased by BYU-Hawaii to spruce up the campus for their Centennial Celebration. 

A visit to the Waimanalo nursery confirmed this information when PM infestations were found on hibiscus plants.  It was disclosed that the nursery obtained some of the infested hibiscus from Maui, where the PM was first detected in Hawaii in May 2004. On Oahu, the PM was subsequently found in Downtown Honolulu and Hawaii Kai. So far, on Oahu, only generalist predators like syrphid larvae, brown lacewings, and ladybugs have been found in association with this mealybug.  On Maui, however, a wasp, tentatively identified as Anagyrus sp. prob. loecki, has been found to parasitize the papaya mealybug and is exerting some control. A PM infestation was reported in June 2006 on some mature, fruiting, papaya trees at a Mililani residence in Central Oahu. It may have become established via a hibiscus plant that was purchased by the homeowner from a garden store in Waikele although he did not recall any infestations on the plant after the purchase. Ornamental plants, including hibiscus, are distributed to garden stores by nurseries in Waimanalo, where the PM is now well established. A follow-up survey of the Mililani infestation disclosed that the pest had already dispersed into the neighborhood. Heavy infestations were observed on a hedge of hibiscus, a papaya tree, and a roseflowered jatropha shrub.

Four shipments of parasitic wasps for biocontrol of  the PM had been sent in June 2005 from a USDA affiliated laboratory in Puerto Rico to the HDOA Insect Quarantine Facility in Honolulu. Propagation of Pseudleptomastix mexicana Noyes and Schauff, one of three species of PM parasitoids, has progressed well and host specificity studies have been initiated following colonization. Rearing of the other two parasitoids, Acerophagous papayae Noyes and Schauff and Anagyrus loecki Noyes, was not successful and they failed to colonize. In the lab, P. mexicana appeared to be the most dominant of the three encyrtid species. After a while, the host plants for rearing the mealybug was switched from potato sprouts and sweet potato plants, used by the USDA lab, to papaya plants in an attempt to increase host density and parasitoid production.