Final Report
Hawaii Invasive Species Council
Research and Technology Program
Project title:
Evaluation of pathogens in Costa Rica for biocontrol of Miconia calvescens
HISC funds: $7,700
Principal investigator:
Tracy Johnson
Hawaii Volcanoes National Park Quarantine Facility
Institute of Pacific Islands Forestry
USDA Forest Service, Pacific Southwest Research Station
P.O. Box 236
Volcano, Hawaii 96785
Ph: 808-967-7122
E-mail: tracyjohnson@fs.fed.us
Summary of project
Building on investigations of Miconia pathogens conducted in Brazil in recentyears, this project provided preliminary evaluation of three pathogens known to occur inCosta Rica. Because pathogen studies in Brazil indicate that Brazilian pathogens tend notto infect Hawaii’s biotype of Miconia calvescens, we have turned to Costa Rica forrelated pathogens that may be better adapted to Hawaii’s Miconia calvescens, whichappears to be a closer match to biotype(s) in Costa Rica. This project was conducted byAnna Dietrich, a student from Leibniz University in Hannover, Germany, as the focus of
her thesis.
Two species of Ditylenchus nematodes were studied. D. drepanocercus, known
from detailed studies in Brazil, was biologically similar in Costa Rica. This nematodecaused angular yellow spots on the leaves of M. calvescens and its host range appeared tobe restricted to the genus Miconia. Damage from this nematode was never severe, andtherefore its potential for biocontrol seems low.
Another Ditylenchus sp. caused galls on Miconia calvescens and a few otherMiconia species and Clidemia species. Artificial inoculation with this nematode wasdemonstrated, but not with great consistency. The severity of damage was always low on
M. calvescens, however this nematode has very high potential as a biocontrol agent for
Clidemia hirta and was successfully imported to Hawaii where it is under quarantine
evaluation at the Hawaii Department of Agriculture.
The fungus Coccodiella miconiae from Costa Rica, which forms small pimples onleaves, was proven to infect Hawaiian M. calvescens for the first time. Although thispathogen also was imported to quarantine in Hawaii, it continues to be challenging topropagate. Thorough host testing of Hawaiian plants will require some additional efforts
to overcome this challenge.

Project Objectives:
1) Collect and propagate Coccodiella and Ditylenchus from field sites in Costa Rica.
Accomplishment: Pathogens were collected from several sites representing a wideecological range across Costa Rica. Propagation was generally challenging, however amethod for maintaining the gall-forming nematode was demonstrated, and this species
has now been successfully maintained in quarantine for over 1 year.
2) Test pathogenicity of collected pathotypes on plants of the Hawaiian biotype ofmiconia.
Accomplishment: Due to a shortage of Hawaiian plants of useful size in Costa Rica at
the time of this study, our work on this objective was limited. The inconsistent successwith inoculation also was a problem for testing Hawaiian plants. We were able todemonstrate Coccodiella infection of a Hawaiian plant under field conditions, which wasa first anywhere and a significant breakthrough after many years of failures with
Brazilian strains of this fungus. Also both Coccodiella and the gall-forming Ditylenchus
have since been cultivated at least to some degree on Hawaiian M. calvescens by Eloise
Killgore at the Hawaii Department of Agriculture.
3) Document courses of infection and impacts on greenhouse plants.
Accomplishment: Inoculation of greenhouse plants was not consistently achieved, butobservation of the infection and impact was documented closely for the gall-forming
nematode. Gall development seemed to originate near vascular tissue. Impact seemed
relatively mild on Miconia calvescens in contrast with severe stunting on Clidemia spp.
4) Evaluate specificity of pathogens through field observations and inoculation tests.
Accomplishment: Field observations of a large diversity of plants indicated that all threepathogens have a host range restricted to melastomes, and probably to a few species ofMiconia and Clidemia, two closely related genera. Inoculation tests will need to berepeated under conditions that ensure consistent infection of control plants.
5) Obtain export permit and ship inoculum of at least one pathogen to Hawaii
Department of Agriculture.
Accomplishment: Both Coccodiella miconiae and the gall-forming Ditylenchus sp. weresuccessfully imported to Hawaii in November 2006 for quarantine evaluation at theHawaii Department of Agriculture.
Detailed results and photo documentation are reported in the attached thesis of Anna
Dietrich:Dietrich, A. 2006. Evaluation of Pathogens from Costa Rica for Biological Control ofMiconia calvescens in Hawaii; Diplomarbeit im Studiengang Biologie, Leibniz
Universität Hannover.