Draft environmental assessment for miconia biocontrol completed
Butterfly May Help Manage Miconia in Forests
A draft environmental assessment (EA) for the release of a biological control insect to manage invasive miconia trees has been filed by the Hawai`i Department of Agriculture (HDOA). In an extensive collaborative research effort involving the U.S. Department of Agriculture Forest Service (USDA-FS), the University of Costa Rica (UCR), the Department of Land and Natural Resources (DLNR) and HDOA, the EA proposes to release a butterfly that is the natural enemy of Miconia calvenscens, a tree that is considered one of the state’s most noxious weeds and a major threat to Hawai`i’s forests and watersheds.
Miconia trees are native to tropical America. In Hawai`i, their rapid growth and large purple leaves take over the forest ecosystem, blocking sunlight and outcompeting native plants. The state has struggled since the 1990s to manage miconia’s aggressive encroachment onto public and private lands.
The 20-year biological control research project studied the miconia butterfly, Euselasia chrysippe, which in its caterpillar stage feeds in tight-knit groups of 40-80 or more on the leaves of miconia. In the plant’s native range of Costa Rica, the caterpillars eat several species in the genus Miconia, effectively controlling the plant’s invasiveness.
Testing by entomologists at the UCR and the USDA-FS in Hawai‘i has shown the miconia butterfly feeds only on miconia and its closest relatives, all members of the melastome family. Melastome plants are all non-native weeds in Hawaiʻi, so predation effects of the butterfly are expected to be beneficial to state forests with no negative impacts on other plants. The EA was funded by DLNR.
“This collaborative effort between state, federal and Costa Rican researchers has provided a promising new tool in the management of miconia in Hawai`i,” said Phyllis Shimabukuro-Geiser, chairperson of the Hawai`i Board of Agriculture. “Further reviews of the EA will also be conducted by HDOA and the Hawai`i Board of Agriculture.”
HDOA conducted the first exploration for natural enemies of miconia within its native range in 1993, and the miconia butterfly was one of the candidate species identified for use as a biocontrol agent. In the early 2000s, the butterfly was re-collected and reared by UCR scientists under USDA-FS direction. From 2005 to 2015 researchers in Costa Rica and Hawai‘i studied the biology and host-specificity of the butterfly to test its safety and effectiveness for biocontrol.
“Miconia is actually hard to find in Costa Rica,” says Tracy Johnson, USDA-FS entomologist overseeing the research since 2000. “This butterfly is one of many specialized natural enemies important for keeping miconia in check and in balance with its ecosystem. Our hope is that several different enemies – that each attack miconia in a different way – can be used for long-term biocontrol in Hawai‘i.”
The miconia butterfly is the first insect to be proposed for miconia biocontrol, while research continues on several other promising natural enemies. One other agent, a fungus that causes leaf spots, was introduced from Brazil in 1997. The fungus is now widespread in the state, but its damage has had limited effect on the fast-growing tree.
The draft EA is available for review at the Hawai`i Department of Health’s Office of Environmental Quality Control (OEQC) website at: http://oeqc2.doh.hawaii.gov/The_Environmental_Notice/2020-04-23-TEN.pdf
Public comments may be submitted to OEQC by May 26, 2020 at that website.
Once the public comments are compiled, the issue will go to the HDOA Plant and Animals Advisory Committee for review and approval, then forwarded to the Hawai`i Board of Agriculture for final approval. USDA Animal and Plant Health Inspection Service will also conduct a review of the EA to decide whether to issue a permit for the release of the miconia butterfly.