HISC enews issue 25

Smithsonian scientists call Miconia "the plant that could destroy the Hawaiian forest." photo by Ryan Smith

Aloha Kakou,

The 2009 International Miconia Conference, “Pulling it all Together,” will be upon us in a matter of days. The conference will engage scientists, resource managers, field technicians and funding agencies in the exploration of the challenges and success associated with Miconia invasions across the Pacific. This eNews highlights some of the Biocontrol projects the HISC supported in order to address Miconia here in Hawaii.

The conference is set for May 4-7 on Maui, and is being hosted by the Maui Invasive Species Committee, more information is available at http://www.hear.org/conferences/miconia2009.

I'm looking forward to seeing some of you there,
Patrick Chee

Invasive Species Coordinator

Research & Technology Grants: Miconia and Biocontrol

Hawai‘i Invasive Species Council (HISC) supports research projects that include investigations into promising biocontrol measures for major forest weeds, such as Miconia calvescens.

Field and laboratory studies have included searches in the forests of Costa Rica, Brazil and Mexico to locate populations of M. calvescens within its native range and to identify insect and other natural enemy species present in native habitats, obtain host specificity data and evaluate the suitability of potential biological control agents for release in Hawai‘i. Scientists have also collected herbarium specimens and DNA samples of M. calvescens for further study.

The aggressive forest invader, Miconia calvescens, has been the focus of chemical and mechanical control in Hawai‘i since it was placed on the state's noxious weed list in 1992. While herbicides and physical removal have yielded significant progress, complete eradication, especially in remote forested regions, is not feasible. Scientists now confirm biological control as the best possible strategy for sustainable control of Miconia.

Biological control of weeds requires the deliberate introduction of exotic herbivores and pathogens to reduce an invasive weed's population density. Components of this strategy include the exploration of a prospective biocontrol agent in its native range, evaluation of the agent, and eventual release and monitoring.

More than 75 potential biocontrol agents for Miconia have been investigated. Biological control of weeds requires the following:

Determination of a need
Search for potential agents
Selection of the most effective agents
Host range surveys
Introduction and establishment of the agent
Evaluation of its effectiveness

April 30, 2009

HISC provided funding support for the following research projects:

Survey for Potential Biological Control Agents for Miconia calvescens in Southern Mexico. Alec McClay, McClay Ecoscience

A survey for potential biological control agents was conducted in southern Mexico. Miconia's occurrence, yet low density, in its native range suggests that environmental factors, such as insects and plant diseases, limit its populations. Researchers recommend further surveys to locate additional populations at varied times of the year, further document natural enemies and investigate their host specificity, study population dynamics, and collect DNA samples to aid in selecting the best-matched biocontrol agents.

Evaluation of Pathogens in Costa Rica for Biocontrol of Miconia calvescens. M. Tracy Johnson & Anna Dietrich

Studies in Costa Rica found potential biocontrol agents in the leaf fungal pathogen Coccodiella miconia and the gall-inducing parasitic nematode Ditylenchus drepanocercus. Further natural enemies such as the stem-boring weevil Cryptorhynchus melastomae and the fruit feeding weevil Anthonomus monostigma, the leaf feeding caterpillar Euselasia chrysippe, a leaf rasping sawfly Atomacera sp., a fruit feeding moth (probably Mompha sp.), the inflorescence feeding butterfly Thecla opisena and the leaf rolling moth Ategumia sp., were observed and are now being further tested in terms of their suitability and specificity.

Quarantine Testing of an Insect for Biocontrol of Miconia calvescens. M. Tracy Johnson

Researchers imported the psyllid Diclidophlebia lucens, a sap-sucking leaping insect from Costa Rica to the Volcano quarantine facility, operated by USDA/APHIS. Insect colonies were tested for two-and-a-half years on 28 plant species, many naturalized melastomes found in Hawai‘i. Its impact on Miconia was deemed limited.

Ecological, Hydrological and Economic Impacts of Miconia in Hawai‘i. ENTRIX, Inc.

A research scoping team was sent to Tahiti, where Miconia has greatly impacted native biodiversity and watershed viability, to assess the feasibility of quantifying Miconia's hydrological and economic impact to model its threat in Hawai‘i. A biocontrol was introduced 10 years ago. The fungus spread naturally beyond the initial treated area and is now found on all the islands. The fungus creates holes in the leaves of mature trees and causes some defoliation, allowing sunlight to penetrate the canopy and reach the forest floor. In areas where the biocontrol has been effective, native and endangered plants have returned. The biocontrol also attacks and kills seedling Miconia plants. The survey laid ground for future studies on cultural impacts from invasive plants; the biocontrol experiment may be used as a case study to illustrate the potential benefits of biocontrol, its cost effectiveness and its benefit to biodiversity.

Accelerated Evaluation of Insects in Costa Rica and Brazil for Biocontrol of Miconia calvescens. M. Tracy Johnson

Evaluation of insects in Costa Rica and Brazil sought to obtain life history, rearing methods, host specificity and impact in the field for prospective agents for biological control, especially two leaf-feeders, the sawfly Atomacera petroa and the leaf feeder Antiblemma leucocyma. Five other species were also investigated: the fruit-galling wasp Allorhogas sp., the inflorescence [flower] feeding moth Mompha sp., the butterfly Erora opisena and two related species, the fruit-eating beetle Apion sp. and the leaf roller Ategumia dilecticolor.

Ecology and Impact of Allorhogas sp. (Hymenoptera: Braconidae) and Apion sp. (Coleoptera: Curculionoidea) on Fruits of Miconia calvescens DC (Melastomataceae) in Brazil . Francisco R. Badenes-Perez & M. Tracy Johnson

Two fruit-feeding insects, a gall wasp Allorhogas sp. and a beetle Apion sp. were evaluated in their native habitat in Brazil as potential biological control agents of Miconia. This is the first study of fruit-feeding herbivores of Miconia in Brazil and the first discovery of a gall wasp attacking this weed. Experimental tests of host specificity on both potential biocontrol agents require further study.