Project to control miconia with butterflies could roll out within year | News, Sports, Jobs

Euselasia chrysippe caterpillars munch on a miconia leaf. State officials hope that the introduction of the caterpillar, which feeds in groups, will help fight the invasive miconia in Hawaii. PABLO ALLEN photo

Over the next year, a butterfly species may take flight in Hawaii as a form of biocontrol to fight invasive miconia plants, which is known as “the green cancer” of the Pacific and currently plagues East Maui.

The state Department of Agriculture and the state Department of Land and Natural Resources had proposed the field release of the butterfly (Euselasia chrysippe) on state lands as a way to mitigate the growth of the noxious weed native to Central and South America.

Maui and Hawaii island have large infestations of miconia, and populations of the plant are also found on Oahu and Kauai.

Efforts to control miconia started in East Maui in 1991. Between then and 1993, more than 20,000 plants were removed from Hana. The plant threatened Hawaii’s forests and was declared a noxious weed in 1992. It’s long been considered one of Hawaii’s most invasive plants, according to the final environmental assessment for the project, which was published last week in the Office of Environmental Quality Control’s “The Environmental Notice.”

Each plant can produce more than 20,000 seeds per fruiting season, and each seed may remain viable for more than 16 years.

Golden Sombermark butterflies, or Euselasia chrysippe, emerge from pupal cases. The butterflies will be used as a biocontrol agent against the invasive miconia that has taken over forests on Maui and other islands. KENJI NISHIDA photo

Miconia has massive leaves and is shade-tolerant, blocking much-needed sunlight to the plants growing below them. Their shallow roots also destabilize soil and can lead to landslides and/or runoff.

Invasive species experts have tried controlling miconia using herbicide and targeting plants from a helicopter.

“In the hills above Hana, Nahiku, and Keanae, the Maui Invasive Species Committee crew hikes day in and day out looking for and pulling miconia plants,” said MISC Manager Adam Radford in written testimony included in the report. “Because E. chrysippe is limited to feeding on a small pool of closely related species, all of which are invasive, its release is expected to be beneficial to Hawaii’s forests and hydrology, and adverse effects are expected to be negligible, leveling the playing field for control efforts.”

The small yellow butterflies’ caterpillars feed externally on leaves of several species of miconia. The species has gregarious larvae, meaning that they flock together and live in big groups. Larvae hatch from large egg masses and continue “to molt and move in unison to feeding sites,” which optimizes foraging, according the DLNR website.

Therefore, this species of butterfly was found to be the “most promising” leaf-feeding biocontrol as it can “inflict more damage to miconia leaves,” according to the EA.

The DLNR told The Maui News last week that the anticipated timeline for the initial releases would be within a year from now, including the time it takes to get all the permits. However, it could be delayed if the regulatory process is slow, the department said.

It will likely take multiple years for the biocontrol insects to be seen throughout the environment, the department added, as it takes “time for the populations to grow and spread.”

After the initial release, state and federal land management agencies will closely monitor the effectiveness of the biocontrol efforts. Although specific methods have not yet been developed, it’s likely that monitoring staff will modify aerial detection techniques already in development, the EA said.

“The USFS (U.S. Forest Service) and partners have done extensive research to make sure these two insects are safe for release in the state of Hawaii (findings summarized in the FEA), and will be the group to import the insects into their quarantine facility and implement initial releases into the wild,” the DLNR said in an email. “DLNR and other land management agencies may then assist in distributing and monitoring these insects as needed.”

Butterfly populations could be self-sustaining within one year with a few staff working only part-time, which is estimated to cost $60,000 for technical support. Additional funding, between $60,000 to $100,000, would support an organized effort to monitor impacts and success over the first two years following release.

Additional funds may be required to increase the distribution and landscape-scale spread of these organisms, the DLNR said.

“It is worth noting that many biocontrols have a track record of being extremely cost-effective (in the) control of invasive species,” the department said.

Organizations like Maui Conservation Alliance and East Maui Watershed Partnership support the biocontrol of this invasive plant.

“Miconia calvescens has been determined by EMWP to be one of the most invasive weeds, with the greatest potential to permanently disrupt the watersheds of East Maui,” the EMWP wrote in written testimony.

The partnership “believes that biological control of Miconia calvescens in Hawaii is an important tool for management of this problematic species.”

* Dakota Grossman can be reached at dgrossman@mauinews.com.

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