2019 — Page 2 — Maui Invasive Species Committee (MISC)

While it may look healthy at first glance, this young naio plant is under attack from a tiny invasive sap-sucking insect known as the naio thrip. Initial symptoms are a crumpling effect on newly sprouted leaves. The pest is currently known only from O’ahu and Hawaiʻi Island — OISC file photo.

From Maui’s coastlines to our mountain slopes, the naio tree provides shelter for native animals and helps prevent erosion. Naio is a shape-shifter: it can be a crawling prostrate shrub or an 80-foot tall towering tree. Itʻs versatile and adaptable. Along the shore, naio plants easily withstand the constant salt spray. At the top of Haleakalā, these indigenous plants endure bracing cold and wind. But the hardy naio trees of Hawaiʻi are at risk from a minuscule, sap-sucking insect, the naio thrip.

At 1/20^th of an inch, about the size of the comma in this sentence, the naio thrip is so tiny it is easily overlooked, but can wreak havoc on naio trees. Within four hours of a thrip beginning to feed on a naio plant, the munched leaf will start to curl. After months of feeding, the plant becomes misshapen and crumpled. Eventually, the thrips will kill naio trees. Young plants are particularly vulnerable.

A young naio plant shows early symptoms of naio thrip infestation – curling and discoloration to the new leaves. — OISC file photo.

The minute thrips were initially found on Hawaiʻi Island in 2008. Infestations there werenʻt found soon enough and many stands of naio have since perished. Resource managers knew it was only a matter of time before the pest spread. To reduce the risk to naio elsewhere, the Hawaiʻi Department of Agriculture implemented a quarantine on naio, prohibiting the movement of the plant from Hawaiʻi Island. Resource managers statewide collaborated on early detection and rapid-response plans specific to each island, recognizing the likelihood that these insect pests could spread throughout the island chain.

So in November 2018, when a native-plant enthusiast on Oʻahu saw strange galls and crumpling on new growth of a naio, and posted a photo online, the response team was prepared for action. Rachel Neville, manager of the Oʻahu Invasive Species Committee (OISC), reports that the survey team had inspected 619 naio plants within a month of the post.

A size comparison of the naio thrip to a thumb. An early detection and rapid response plan in place on Oahu has guided containment efforts after the pest arrived there in November of 2018. — Oahu Invasive Species Committee photo.

“Having a rapid response plan for this detection was so helpful. We had a list of naio that should be checked island-wide and all the agencies and landowners came together to help delimit. We were able to determine the extent of the infestation in one week, which meant treatment got underway very quickly,” says Neville. During island-wide surveys, the response team (including staff from a half-dozen resource management programs) found only 42 infested plants, all of which were in urban settings, isolated from natural areas and wild populations. All infected plants have been treated and the survey team is continuing to check naio for signs of thrips. Citizen scientists are helping by submitting photos through the OISC Adopt-a-Naio program.

Naio thrips have yet to be found on the Valley Isle. The Maui County Early Detection and Rapid Response plan, developed by eight resource-management and protection organizations, calls for monitoring over 30 naio populations across Maui, all of which were thrips-free as of February 2019. The surveys are repeated every six months.

You can help. If you have naio in your yard, or know where there are some, check them regularly for signs of thrips: crumpling and curling leaves. Find out more about naio thrips and the Maui County Early Detection and Rapid Response Plan online at https://dlnr.hawaii.gov/hisc/info/invasive-species-profiles/naio-thrips/

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, “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.

This article was originally published in the Maui News on March 10th, 2019 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Read more Kiaʻi Moku articles.

Large beetles have begun to spread across Puna but have not yet been detected on other islands. They pose a threat to fruit growers on the island and throughout Hawaii. Native to Queensland, the *Acalolepta aesthetica*, longhorned beetles are dimpled and fuzzy on their abdomens. — Photo courtesy of Big Island Invasive Species Committee.

In 2009, a resident of Orchidland subdivision in Puna on Hawaiʻi Island found a strange beetle with extremely long antennae on the screen door. This report marked the first detection of a new species of longhorned beetle, Acalolepta aesthetica, in Hawaiʻi and the United States. Lacking an official common name, the beetle is called the Queensland longhorn beetle, reflecting its native home in Australia.

Despite survey efforts by the Hawaiʻi Department of Agriculture, the beetle wasn’t detected again for years, but that first incursion wasn’t a one-off and its population continued to grow. Four years later it was seen again. Sightings increased as the beetles spread across Puna. Over the last 3 months, the Big Island Invasive Species Committee has received over a dozen reports.

The arrival of this new insect has officials with the Hawaiʻi Department of Agriculture (HDOA) concerned. According to HDOA entomologist Darcy Oishi, the Queensland longhorned beetle could significantly damage citrus and other trees. The larvae tunnel through living wood creating big galleries, similar to termites, but on a much bigger scale. Oishi says, “They make these giant weeping wounds in branches or the trunk of a tree. The damage can cause dieback in a limb or the death of a tree.”

“They make these giant weeping wounds in branches or the trunk of a tree. The damage can cause dieback in a limb or the death of a tree,” says Oishi.

Not much known about this beetle, perhaps because it’s not a pest elsewhere. Its arrival in Hawaiʻi marks the first time this beetle has acted invasively with potential impacts only now being realized. The list of trees damaged by beetle larvae continues to grow. It’s been found tunneling through lemons, limes and other citrus; Polynesian-introduced trees such as ulu (breadfruit) and kukui; favorite food crops like cacao (chocolate) and possibly avocado; and introduced species such as gunpowder trees and sago palm. As the current world expert on the beetle, the Hawaiʻi Department of Agriculture has not identified any natural enemies in Hawaiʻi nor any effective controls methods.

Complicating research on control options is the presence of native longhorned beetles in our state. Important both as wood decomposers and food for native birds, our Cerambycid beetles are one of the many native insects that show amazing rates of adaptive radiation. From what entomologist estimate was three distinct arrivals, over 120 species evolved. One of the largest native insects in Hawaiʻi is a Cerambycid beetle; measuring 2 inches from tip to tail with sweeping antennae as long as its body, Megopis reflexa is closest in appearance to the invasive Acalolepta aesthetica.

The new wood-boring pest is not yet known from Maui or any of the other Hawaiian Islands, but farmers and residents can take steps to prevent its arrival. The best way to keep it from moving interisland is to not bring green woody material between islands, particularly if the vegetation shows signs of damage, such as weeping wounds where a beetle may have laid its eggs and larvae entered the tree.

The larvae of *Acalolepta aesthetica*, a longhorned beetle from Australia, leaves large weeping holes in tree trunks of food crops like citrus and cacao. — Photo courtesy of Hawaii Department of Agriculture.

Be alert to sightings of the beetle, often attracted to house lights at night. The adult measures from 2-4.5cm (3/4-1 ¾ inches) in length. The antennae on the male are twice as long as the body – giving rise the moniker “longhorned.” Antennae on the female are shorter. On either side of the thorax (the body part behind the head) are two thorn-like spines. The abdomen is dimpled and looks as though covered in peach fuzz. In contrast, the native Megopis beetle has ridges running down the abdomen, giving it a striped appearance.

There is a native longhorned beetle – *Megopis reflexa* – that is nearly the same size as the invasive Queensland longhorned beetle. Look for stripes running the length of the body. –Photo courtesy of Ross Kamimoto

Oishi also suggests looking for wounding on trees. The beetle larvae can be even larger than the adults and as they leave the tree to mature, they leave behind large holes, up to 1.25 cm (1/2 inch) in diameter, as big around as a pinky. Other indications are sawdust-like frass being pushed out of holes on the trunk, girdling on trunk, sap oozing from where the adult laid eggs, and branch dieback and drop. Find more details and the official pest advisory on the HDOA website: http://hdoa.hawaii.gov/pi/ppc/new-pest-advisories/.

On Maui, report any suspected sightings. Collect the beetle and contain it in a secure container. Take clear digital photos of the beetle and record the location, type of plant or tree, date, and how you found it. If you see damage on a tree, take photos. Use an object (coin or ruler) for reference. Email the photos and the information to HDOA.PPC@HAWAII.GOV or report it online through 643PEST.org.

This article was originally published on August 10th, 2018 as part of the Kiaʻi Moku Column for the Maui News.

Sap-sucking insect threatens native naio trees

Invasive longhorned beetle bores into fruit trees, threatening crops

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