Biological Control Section Project, FY 2006
Miconia [Miconia calvescens DC]. Due to its aggressive, invasive nature, miconia continues to be a major threat to ecosystems in the Hawaiian Islands, and exploration for, and research to utilize, other biological control agents continue to be ongoing projects. In 1997, Plant Pathologist Robert Barreto of the University of Viçosa, Viçosa, Brazil, identified a foliar nematode on miconia in Brazil and Costa Rica. This newly described nematode, Ditylenchus gallaeformis, causes severe leaf distortion and galling and was proposed by Dr. Barreto as a potentially good biocontrol agent.
In March 2006, nematode galls collected in Brazil were shipped to the HDOA Plant Pathogen Quarantine Facility (PPQF) for host range testing and a colony has been established. However, infection of this nematode onto miconia plants in the quarantine facility has been painstakingly slow, prompting Dr. Barreto to conduct a reassessment of the parasitism of the nematode to the Hawaiian miconia biotype. He is collaborating with Dr. Tracy Johnson of the USDA Forest Service Quarantine Facility at Hawaii Volcanoes National Park on the island of Hawaii to test the nematode in Costa Rica, where the miconia biotype more closely matches the biotype in Hawaii. A graduate student was hired to isolate the nematode in Costa Rica and to determine its pathogenicity to the Hawaiian miconia biotype.
Shipments of the nematode and another fungal pathogen, Coccodiella miconiae, on miconia to the PPQF in Honolulu are scheduled for August 2006. Meanwhile, the biocontrol fungal pathogen Colletotrichum gloeosporioides f. sp. miconiae continues to be active in the wet Onomea area of East Hawaii and may be keeping miconia plants from becoming the dominant vegetation in that locality.