Maui, Island of Hawaii, home of a beetle weed control project | News, Sports, Jobs

Adult Syphraea uberabensis beetles feed on cane tibouchina. Studies have shown that the plant struggles to regrow after a beetle attack. Lon Bulgrin photo

Starting in high-density areas on Maui and Hawaii, a Brazilian beetle that eats cane tibouchina and other related weeds could be released over the next year to help prevent invasive plants from taking hold. the top.

The state’s departments of agriculture and lands and natural resources said these insects, Syphraea uberabensis, could help control cane tibouchina, known as Tibouchina herbacea, a noxious weed native to southern from Brazil, Uruguay and Paraguay. It now grows thick in the forests of Maui and surpasses native species.

Syphraea uberabensis is a small beetle whose adults and larvae feed on the invasive plant in the beetle’s native region in Brazil, according to the project’s final environmental assessment that was published last month in the Office of Planning and Development. sustainable development. “Environmental notice”.

The DLNR plans to release the beetles onto state land as a form of biological control of invasive plants.

Each tibouchina can produce hundreds of seed capsules which can in turn produce up to 700 seeds the size of a grain of sand. These tiny seeds are easily dispersed by wind or by wildlife, humans, vehicles or water, according to the EA.

Notable for its pink and purple flowers and tall, hairy stems, cane moss is an invasive weed found in Hawaii’s pastures and forests. Photo by FOREST and KIM STARR

In Hawaii, the erect semi-woody shrub has become predominant in the forests of Maui, Molokai, Lanai, Oahu, and the island of Hawaii. Once established, tibouchina cane becomes very dense and difficult to traverse, which can displace native plants and vegetation.

Attempts to control the plant have included the use of herbicides and mechanical removal, but these methods have proven costly and not very effective, The Nature Conservancy said, which is why the state is now turning to biocontrol.

Residents involved in conservation work supported the project in letters to the state.

“This weed is very difficult to deal with as it is able to access all parts of the mountain as it is dispersed by the wind,” Kula resident Andrei Stanescu, a field assistant who works in the Mauna Kahalawai watershed, said in written testimony included in the EA. “Using this beetle as a biocontrol would help us slow the spread of Tibouchina and because hand-pulling this weed often causes its seeds to spread and opens up new habitat for its seeds to spread locally in the disturbance created by uprooting.”

Mauna Kahalawai Watershed Partnership operations manager Olowalu resident Jill LaBram said this weed is particularly bad in “Areas disturbed by pigs and affected by landslides.”

Cane tibouchina grows along the Waihee Ridge Trail in Maui in 2020. FOREST and KIM STARR photo

“It also impacts streams and waterways,” LaBram wrote in a letter. “We need this agent because we have no other practical recourse to control him.”

According to the DLNR, beetle populations should reach effective levels on the target plant within a few years at release sites.

“Biocontrol can provide a long-term, cost-effective and environmentally friendly solution,” says the report.

The costs of distributing the insect for management will be relatively low, according to the report, and the facilities, equipment and personnel needed to rear the insect are simple and minimal.

Establishing self-sustaining populations at statewide field sites can probably be done in a year with just a few part-time employees – around $40,000 for a technician over a year. There may also be other costs, which were not specified in the report.

The pre-release study was conducted over two years with a $75,000 grant from the Forest Service. Another investment of $75,000 will likely cover the costs of post-release monitoring.

Agencies contributing to this effort include the USDA Forest Service, the state Department of Agriculture, and the DLNR. Invasive species committees, watershed partnerships and other weed management stakeholders are expected to be active partners in identifying release sites and helping to monitor initial establishment. at some release sites.

The DLNR told The Maui News last week that the expected timeline for early releases would be within a year, including the time needed to obtain all permits. However, it could be delayed if the regulatory process is slow.

From there, it could take several years for the biocontrol insects to become populated and visible throughout the environment, the department added.

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


Today’s breaking news and more to your inbox



Lynn A. Saleh