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Mystery of the QLB: how did it get here?

Posted on May 19, 2020 by Franny Brewer

Moringa logs dropped off at HDOA in Hilo after the tree was attacked by QLB. Photo courtesy S. Chun, HDOA.

In August 2019, a resident from Puna submitted logs to the state Department of Agriculture office in Hilo. Those logs were the remains of a moringa tree, another victim to the voracious appetite of an Acalolepta aesthetica, which has come to be known locally as the Queensland Longhorn Beetle (QLB). On that morning, HDOA entomologist Stacey Chun piled the logs in the corner of the insect containment unit and reluctantly added moringa to the growing list of tree species being attacked by QLB.  Already, the insect had been confirmed in several kinds of trees, including citrus, kukui, breadfruit, and cacao. It was the cacao farmers who had first raised the alarm on QLB in 2018, when growers noticed healthy, producing trees suddenly devastated by a mysterious insect. 

The case of A. aesthetica illustrates the difficulty of managing new invasive pests. Although it was first identified from a sample turned in to the HDOA office in 2009, no subsequent specimens were reported for several years. The Coordinating Group on Alien Pest Species (CGAPS), which provides tools and guidance for invasive species response in Hawaii, has estimated that one new insect species per day arrives at Hawaii’s ports. Most of the creatures that get here accidentally are individuals who will not survive in their new environment. Some will find their way and naturalize, but never rise to notice because they don’t cause much disruption to the world around them.  But a handful will become pests that make headlines: coqui frogs, little fire ants, semi-slugs, two-lined spittlebugs. These are the introduced species that thrive in the Hawaiian environment, free from the predators and diseases that kept them in check in their home ranges, and able to exploit the environmental niches left open in an isolated island ecosystem.

Queensland Longhorn Beetle

Queensland Longhorn Beetle captured in Puna.

When a few more of the new longhorn beetles turned up in 2013, it was clear that the insect had found a way to survive and breed in Hawaii. It was not clear what this meant. An investigation into the insect’s background revealed little, only that it was from Queensland, Australia and not known to be living anywhere else in the world – until it reached Hawaii. In Queensland, lush and verdant tropical forests surround landscapes of agricultural production, and never was this beetle reported as a pest. As just one of dozens of Cerambycid (longhorn) beetle species found in Queensland’s forests, this dull brown, cockroach lookalike didn’t particularly stand out. Very little was known about its life cycle or habits, or even which tree species it favored in its home range. 

How it arrived in Hawaii was even more of a mystery. From genetic tests done by Dr. Sheina Sim at the USDA Agricultural Research Service in Hilo, it is clear that all of the QLB in Hawaii are descendants of the same line, meaning there had been only one introduction event.  But due to the Jones Act, Hawaii receives very few commodities directly from other countries. Most goods crossing the Pacific must first head to the mainland to a designated international port, then be shipped back to Hawaii from there. No direct shipments from Queensland appeared to account for the insect arriving in Puna. 

QLB larvae in dead log

QLB larvae in dead logs. Photo courtesy S. Chun, HDOA.

Clues could be found in studying a closely related member of the QLB’s family, known as the Asian Longhorn Beetle (Anoplophora glabripennis), or ALB. Unlike its Queensland-based cousin, the ALB is a known problem-maker worldwide. In North America, where it was first spotted in 1996, costs of damage and control associated with ALB are now at nearly $1 billion. The ALB is so devastating that some European countries have taken the approach of killing every susceptible tree within a half-mile when a single insect is found. 

The arrival of ALB in the 1990s coincided with the opening of direct trade between the US and mainland China, and the source of the introductions was deduced to be untreated wood packing materials which had delivered hidden larvae along with their cargo. Because the behavior and life history of ALB appeared similar to Hawaii’s new and unwelcome guest, researchers hypothesized that it was possible QLB could have arrived here the same way. But was it possible the larvae could have survived a lengthy trip across the ocean and halfway back again?

The moringa logs in Stacey Chun’s HDOA lab offered up an answer to that question.  Nearly eight months to the day after the logs were set aside, all but forgotten in the QLB insectary, a live adult emerged from the dried wood in April 2020. It had taken that larvae nearly eight months to develop to full adulthood (previously, Chun had recorded adult emergence as soon as 3 months). Eight months was more than enough time for a clutch of insect eggs to have traveled halfway around the world, unnoticed as they slowly developed inside of their wooden nest, to finally emerge as full-grown adults in an unsuspecting new home.

QLB exit hole in log

A large hole in a moringa log where an adult Queensland Longhorn Beetle emerged. Photo courtesy S. Chun, HDOA.

QLB and ALB are not the first of their kind to move into new territories via untreated wood, and unfortunately they will likely not be the last. As humans enjoy the convenience and opportunity that new technology and increasing global traffic have afforded us, we must also contend with the downsides, one of which is the accidental movement of species into places where they have the potential to cause great harm. In the early aughts, in response to multiple infestations of new pests, the US and many other countries adopted a set of requirements that wood packaging material be certified as properly treated to kill pests. These rules were phases in and not fully implemented for several years, which is possibly the window during which QLB came into Hawaii. Subsequent research has also found that not all wood-boring insects are equally susceptible to the prescribed treatment methods, and that the quality and efficacy of the packing wood treatment can vary between manufacturers, so even with enhanced regulations  Untreated or inadequately treated wood remains a potential risk.

More information, including a gallery of QLB photos and tree damage, can be found here. 

Filed Under: Education, News, Slider Tagged With: longhorn beetle, new pest, Queensland longhorn beetle

Queensland Longhorn Beetle

Posted on May 5, 2020 by Franny Brewer

Click here for Beetle Reporting Form. If you are not sure if your beetle is a QLB, you can email a pic to biisc@hawaii.edu for identification.

April 2020 Update.  If you find a beetle: QLB have so far NOT been found outside of known infestation zone (roughly Hilo-Pahoa-Mountain View) in East Hawaii. If you find a suspect beetle anywhere on the island, you can email a picture to biisc@hawaii.edu, or use Facebook to message it to us. We will ID the species and let you know if it is QLB. If you are outside the known infestation zone, it is extremely important that you take a picture so we will know if the beetle has spread.

If you are inside the infestation zone and find a beetle, please report it using this reporting form. Please include a pic if at all possible.  You can also use this form to report tree damage from QLB – again, include pics.

For live, captured beetles, there is potential for pickup. Email us for arrangements.

November 2019 HDOA Update

Update from Hawaii Department of Agriculture Hilo Branch, July 2020

Confirmed host plants:

  • Kukui (Aleurites moluccanus)
  • Breadfruit (Artocarpus altillis)
  • Various citrus (Citrus spp.)
  • Queen Sago (Cycas cirinalis)
  • Cacao (Theobroma cacao)
  • Mulberry (Morus sp.)
  • Trumpet tree (Cercropia obtusifolia)
  • Kalamungay (Moringa oleifera)
  • Norfolk pine cut logs (Araucaria heterophylla)
  • Avocado (Persea americana)
  • Hibiscus (Hibiscus spp.)
  • Croton (Codiaeum variegatum)
  • Elder berry (Sambucus nigra)
  • Gunpowder tree (Trema orientalis)

Unverified, but possible host plants:

  • Loquat (Eriobotrya japonica)
  • Tree spinach, Chaya (Cnidoscolus aconitifolius)
  • Passion fruit (Passiflora edulis var. flavicarpa)
  • Cycads spp. (Encephalartos Horridus, Encephalartos Laurentianus, Dioon Merolae, Microcycas)

USDA-ARS is still collecting live beetles!  If you capture a beetle please bring it to our offices or contact us to arrange pick-up. Need a specimen holder?  Come pick up a jar or container at our office for free any day during the week!

March 2018: An invasive beetle is attacking cacao, citrus, breadfruit, and kukui on the east side of the Big Island. The beetle, Acalolepta aesthetica, is believed to have been accidentally introduced through imported commodities from the Queensland region of Australia. Beetles in this family, the Cerambycids, are wood-borers and are known to burrow into wooden packing materials. Acalolepta aesthetica is related to the Asian longhorn beetle, infamous for devastating forests in North America with estimated costs for control more than $600 million since the 1990s.

The USDA Agricultural Research Service lab in Hilo is currently asking for live specimens of beetles for research. Dr. Sheina Sims and her team are looking to map the beetleʻs genetics, an important tool in early detection when beetles are found in the difficult to identify larval stage. Additionally, working with BIISC and the East Hawaii Cacao Association, the ARS team will be launching a trapping study to determine if there are pheromones or other attractant traps that could be used to find and monitor beetle populations.

This longhorn beetle from the Queensland area of Australia appears to have first arrived in Hawaii about a decade ago. The first sample was turned in from the Orchidland area in 2009, but for several years after, there were no reports.  However, in 2013, HDOA received 3 more submissions, with a handful of beetles appearing each subsequent year.  By 2017, it appeared the beetles had begun to spread, with specimens collected in Hawaiian Acres, Kea’au, and Kurtistown.  In summer of 2018, specimens were captured in Pahoa and Hilo, indicating the beetle may be expanding its territory.

Adult beetles will feed on the bark, branches, and leaves of preferred plants, but the real damage is caused by the larvae. The females lay eggs in wood, usually in stressed, dying, or weakened trees. The emerging larvae will tunnel through the tree’s vascular system, creating tunnels that weaken the wood and interrupt the plant’s ability to transport nutrients and water.  In one case in Puna, an infested Sago palm became so weak it collapsed under its own weight.

In addition to cacao, citrus, kukui, and Sago palms, A. aesthetica may potentially attack other hardwoods present in Hawaii,  from important crop trees to native forest species.

There is no known treatment for an infestation of A. aesthetica.  Adult beetles appear to be attracted to light at night, where they can be collected. HDOA advises that routine IPM insecticidal applications may deter adult beetles from selected areas; however, research is needed to determine how to address beetle infestation. The best strategy is prevention: be very cautious in moving potential host plant species from the infected area between Kea’au and Pahoa. Trees infested with the larvae should be destroyed.

Contact BIISC with a photo via email at biisc@hawaii.edu or on Facebook to report any beetle sightings. Beetles can be also dropped off at our office at 23 E. Kawili St.

Kukui Damage
QLB Life Stages
QLB Damage. Sap and girdling from burrowing larva.
Frass
Pupa found in gallery
Different kinds of longhorn beetles found on the Big Island
Bark stripped by QLB gnawing.
Sap oozing from kukui tree QLB boring
Oozing sap indicates QLB infestation.
Sap oozing from QLB boring.

August 10, 2018 Pest Release by HDOA:

Australian Longhorn Beetle Pest Advisory

Australian Longhorn Beetle Quick Pest Fact Sheet

Filed Under: News, Slider Tagged With: hawaii pest, longhorn beetle, qlb

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