In an effort to manage invasive miconia trees, the state Department of Agriculture is proposing the release of a butterfly known to feed on the noxious weed threatening Hawaii’s forests and watersheds.
Miconia trees are native to tropical America. In Hawaii, their rapid growth and large purple leaves take over the forest ecosystem, blocking sunlight and out-competing native plants, according to the department. 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 in Hawaii has shown the miconia butterfly feeds only on miconia and its closest relatives, all members of the melastome family. Melastome plants are all nonnative weeds in Hawaii, so predation effects of the butterfly are expected to be beneficial to state forests with no negative impacts on other plants, according to the department.
The draft EA for the proposal was published in the April 23 Environmental Notice. It is available online at the Office of Environmental Quality Control website. Comments are due May 26.
“This collaborative effort between state, federal and Costa Rican researchers has provided a promising new tool in the management of miconia in Hawaii,” said Phyllis Shimabukuro-Geiser, Hawaii Board of Agriculture chairperson. “Further reviews of the EA will also be conducted by HDOA and the Hawaii Board of Agriculture.”
The Department of Agriculture 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 scientists under USDA Forest Service direction. From 2005 to 2015 researchers in Costa Rica and Hawaii 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,” said 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 Hawaii.”
The miconia butterfly is the first insect to be proposed for miconia biocontrol, while research continues on several other 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.
Once public comments are compiled, the issue will go to the department’s Plant and Animals Advisory Committee for review and approval, then forwarded to the Hawaii 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.