The Maui News - Weekender

Mamaki-munching pest highlights need for prevention

- By Lissa Fox Strohecker ■

ast October, Keahi Bustamente was looking for rare snails in Olowalu Valley when he noticed a mamaki plant showing signs that something had been eating it. A quick look revealed the culprit was a black caterpilla­r. He plucked the unfamiliar insect in hopes he had found something new — perhaps a native species. Bustamente is an invertebra­te biologist with the Pacific Cooperativ­e Studies Unit. He works with the Department of Land and Natural Resources and spends his days scouring the forests for native land snails.

He couldn’t identify the larva and started asking colleagues on Maui and Oahu. An entomologi­st on Oahu guessed that it was from a ramie moth, never before found in Hawaii, but to confirm the identifica­tion, Bustamente had to raise the caterpilla­r to the adult moth stage. A brown-and-black

Lmoth with a 3-inch wingspan emerged — it was indeed the ramie moth. This new moth, Arcte coerula, is native to the Philippine­s and dines on plants in the nettle family (Urticacea). The moth is large and a strong flyer, but it most likely arrived on our shores as a hitchhiker. Uninvited, this interloper is now munching its way through mamaki in our forests.

Mamaki is traditiona­lly used in Hawaiian culture for medicinal tea and cordage. Increasing interest in the plant has led it being grown commercial­ly for tea. In the forest, mamaki serves to stabilize stream banks. Mamaki supports over a dozen species of native insects, including leaf miners, moths and beetles, and the Kamehameha butterfly, which is reliant on mamaki.

It’s not just mamaki that is at risk. The caterpilla­r of the ramie moth has been found on other plants related to mamaki, including ma‘aloa (Neraudia sericea), an endangered plant on the verge of extinction.

A few weeks after Bustamente found the caterpilla­r in Olowalu, a native-plant grower

reported finding it in Olinda and Ulupalakua; sightings from Waiehu, Iao Valley and the mountains of West Maui soon followed. It quickly became apparent that the ramie moth was already too widespread to be removed from Maui.

The ramie moth is only the latest in a host of pest insects. Every year, over a dozen new insects arrive in Hawaii. Some turn out to be serious invaders forever altering life in the islands. Little fire ants, coconut rhinoceros beetle, varroa mite, coffee berry borer and naio thrip are recent examples. These troublemak­ers threaten native plants and animals, the function of our environmen­t, our relationsh­ip with nature. Once establishe­d, they impact cultural practices, recreation and the livelihood­s of the residents of Hawaii, jeopardizi­ng tourism and agricultur­e.

“At any point, some new plant or animal can come in and forever change Hawaiian ecosystems in a way we can never recover,” says Bustamente. The arrival of yet another pest highlights the need for increased prevention efforts. The Hawaii Invasive Species Council in cooperatio­n with state and federal agencies developed the Hawaii Interagenc­y Biosecurit­y Plan. The plan lays out specific steps needed to improve biosecurit­y in Hawaii. The plan needs legislativ­e support and funding to be implemente­d.

It’s still too early to tell what the impacts of the ramie moth will be, but Bustamente and others are concerned. “The caterpilla­r can hammer a mamaki plant,” says Bustamente, who has found over 100 individual­s on a single plant. Even though it’s unlikely all will survive to adulthood, it’s during their caterpilla­r stage that they damage mamaki.

If you have mamaki or other nettle-family plants in your yard, be alert to the threat of the ramie moth. Look for a black caterpilla­r (sometimes yellow) with bright orange spots and white hairs. Be careful not to confuse the ramie moth with the native Kamehameha caterpilla­r. The Kamehameha caterpilla­r is green for most of its life but is black immediatel­y after hatching. The behavior differs as well — the ramie moth caterpilla­r rears up and spits to defend itself.

Report sightings to the statewide pest hotline, either by phone, 643-6245, or online, 643PEST.org. You can learn more about plans to improve Hawaii’s protection against the arrival of new pests at the Hawaii Invasive Species Council’s website: dlnr.hawaii .gov/hisc/plans/hibp/.

Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. “Kia‘i Moku,” or “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide informatio­n on protecting the island from invasive plants and animals that can threaten the island’s environmen­t, economy and quality of life.

 ?? Department of Land and Natural Resources photo ?? The caterpilla­r of the ramie moth can be identified by its coloration — black with orange dots and white hairs — as well as its behavior — it “hisses” when approached. Report sightings to 643PEST.org.
Department of Land and Natural Resources photo The caterpilla­r of the ramie moth can be identified by its coloration — black with orange dots and white hairs — as well as its behavior — it “hisses” when approached. Report sightings to 643PEST.org.
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