New & Noteworthy: Mosquito, Devil Weed Biocontrol

So Long, Skeeters: The multi-agency effort to save a number of native forest bird species from imminent extinction got a boost June 22, when the state Board of Agriculture unanimously approved a permit allowing the importation of 25,000 male Culex quinquefasciatus mosquitoes that have been inoculated with a foreign strain of the Wolbachia bacteria, ensuring that their mating with local female mosquitoes won’t result in any offspring.

Releasing the mosquitoes into the wild here is intended to suppress the Culex mosquito populations in forests where native honeycreepers are struggling to survive, as temperatures climb and disease-carrying mosquitoes infiltrate the birds’ habitat. Those mosquitos are vectors for avian pox and avian malaria, which threaten to wipe out the critically endangered ‘akikiki and ‘akeke‘e on Kaua‘i, and the kiwikiu and ‘akohekohe on Maui.

University of Hawai‘i at Manoa professors Floyd Reed and Matthew Medeiros requested the special permit from the board to import the mosquitoes, conduct laboratory and field research on them, and eventually release them into the wild. The mosquitoes, originally collected from Hawai‘i, are currently kept at Michigan State University and the University of Kentucky.

The Wolbachia technique has been used successfully outside Hawai‘i to suppress mosquito populations and protect humans from mosquito-borne diseases such as dengue and Zika.

“We have high hopes it will be as effective here in preventing species extinction,” said Michelle Bogardus of the U.S. Fish and Wildlife Service, which is also involved in the effort.

“We are literally seeing forest birds go extinct on our watch and it’s just going to continue. … This [project] is just an absolutely crucial next step for trying to stem that extinction surge,” Dave Smith, administrator for the Department of Land and Natural Resources’ Division of Forestry and Wildlife, told the board.

The Department of Agriculture has determined that an environmental assessment is necessary before mosquitoes are released for either field research or mosquito control. According to DLNR director Suzanne Case, an environmental review is underway for a broader release anticipated in the future.

For more background on this, see our April 2021 Board Talk item, “Fate of Endangered Forest Birds Hinges On Landscape-Scale Mosquito Control.”

Down with the Devil Weed: The Department of Land and Natural Resources is beginning the environmental review process for its plan to release a fly that is known to control the highly invasive Chromolaena odorata, also known as devil weed.

The weed, discovered on O‘ahu in 2011, “aggressively colonizes clearings, wet forests, and agricultural lands, and creates dense monocultures that prohibit other plants from growing nearby. The plant is toxic to livestock, and can be a skin irritant and cause asthma like symptoms for some individuals,” according to a recent solicitation for comments from the department.

“Although the weed has only been detected on O‘ahu and Hawai‘i island, it is expected over time to spread throughout the state as the population on O‘ahu is no longer eradicable,” it continues.

The agency plans to release the stem-galling fly Cecidochares connexa, which has been successfully released in ten countries to control the Chromolaena odorata. It is currently working to determine if the fly is host-specific when tested with plants found in Hawai‘i. If it’s found that the fly won’t impact non-target species, the department will conduct an environmental assessment and file permit applications with the required state and federal agencies.

The DLNR will accept preliminary comments on the project at www.biocontrolha- until July 29.

Stilt Status: The U.S. Fish and Wildlife Service has extended the comment period for its proposal to downlist the Hawaiian Stilt, or ae‘o, from endangered to threatened. The comment period initially ended on May 24, but in response to a request from the public, the agency has reopened the comment period, which now ends on July 23.

It has also scheduled a virtual public hearing on Zoom for July 7, from 6-8 p.m. preceded by an informational meeting from 5-6 p.m.

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