Earth & Sky

Our thanks to the following individuals and institutions who assisted in the preparation of this script:

Dr. Therese Poland
Entomologist
U.S. Forest Service
North Central Research Station

Dr. Robert A. Haack
Entomologist
U.S. Forest Service
North Central Research Station

For more information about the Asian Longhorn Beetle, please visit the following websites:

U.S. Forest Service North Central Research Station Newletter Webage (click on the October/November/December 2000 Issue)

U.S. Forest Service Northeastern Area – Asian Longhorn Beetle Webpage

USDA Animal and Plant Health Inspection Service Asian Longhorn Beetle Webpage

Newsletter of the Michigan Entomological Society Volume 43 No. 4, December, 1998, pages 15-17 (~500k)

Press Release from the Oak Ridge National Laboratory ORNL instrument could spell doom for Asian beetles

Background Information

The Asian Longhorn Beetle (anoplophora glabripennis) is a serious pest that infests hardwood trees. The beetle is not native to North America, but arrived to the continent as a stowaway from China, hidden in solid wood packing materials.

Because the beetles live deep in the trees, they can be difficult to find. Adult beetles are only active in the summer, spending the rest of the year inside trees. Beetle larvae bore into the trunk and branches, causing heavy flow of sap from those wounds. Infested trees have large accumulations of frass (a mix of sawdust and insect waste) at the base of the tree. Adult beetles usually leave round holes, 1/2 inch or larger in diameter, in the bark. Infested trees produce unseasonal yellowing or droopy leaves. Eventually, the beetles can kill the tree.

There is currently no known treatment for trees infested with Asian Longhorn Beetles. There are no known lures or traps to catch the beetles. Scientists are currently investigating insecticides that can be injected into the tree to kill the beetles but not harm the trees. For now, the only way to stop the beetle from spreading to other trees is to destroy the infested tree. These trees are chopped down, chipped, and burnt to destroy the beetle at all its life stages.

Interview with Dr. Therese Poland,
Entomologist at the U.S. Forest Service North Central Research Station

What kind of detector is being used, and how does it work?

It’s an acoustic detector. When the beetles are feeding in trees, their sharp mandibles bite into the wood fibers, making popping and scraping sounds. These sounds can be audible [to the human ear] in a heavily infested log in a lab. But in a big tree in nature, it cannot be heard. Because of these noises, it’s possible to analyse the sound to obtain specific characteristics made by particular organisms.

The instrument is being developed by acoustical engineers at Oak Ridge National Laboratory in Tennessee. They do a lot of work for the Department of Defense in sonar research, for submarines. They’re acoustical data analysis experts.

Initial analysis was done using infested logs containing native woodborers, like the white pine sawyer, a beetle related to the Asian Longhorn Beetle. Other native species were also studied. These infested logs were brought to a lab at Oak Ridge. We could not use Asian Longhorn Beetles in the initial studies because the Oak Ridge lab did not have quarantine facilities. At the lab, hundreds of digital recordings were made of the vibrations. The sound data was analysed to look for similarities and differences for different [woodboring] insects. An algorithm was developed to describe the vibration pattern.

The formula to describe the vibration pattern is general enough that it fits the data for all the bugs studied. It could be fine-tuned in the future to identify by species. The sound pattern for all woodborer bites is similar, a spike followed by ringing.

That pattern is now built into the detector. The detector consists of an accelerometer, a small device that picks up vibrations from the tree or log. A small hole is drilled, a small screw inserted into the hole in the tree, and the accelerometer is attached to the screw so it is in direct contact with the tree. It will pick up vibrations in the wood.

The accelerometer picks up the vibrations. A cable sends the signals to a data acquisition card, then to a laptop or hand-held computer (that has a wristband keypad). In the computer, software containing the bite sound algorithm filters the sound. Data flows continuously into the computer that can process 5,000 bytes of data at a time, looking for a pattern of sound to detect a bite. The sound being sampled has a frequency of about 200 KHz or 200,000 times per second. One megabyte of data is processed every second. Therefore, only portions of data identified by the software as beetle bites are saved.

The software can identify beetle bites for any kind of woodborer, even for insects that are not beetles.

Work is currently being done to fine-tune the detector. Experiments are being done in China and the quarantine lab. Bite sounds are being collected from different types of insects, types of tree or wood, distance of insect from detector, temperature, stage of growth of larvae. These controlled experiments are performed to build an acoustical library to learn sound patterns for different configurations. Small, medium, and large Asian Longhorn beetles, types of trees, different lifestages, distance from detector, will all be studied.

How difficult is it to fine-tune the detector to only pick up Asian Longhorn Beetles?

You don’t want the detector’s detection algorithm to be too specific, it could accidentally miss an Asian Longhorn Beetle. In operational use, the detector will be kept general to pick up other species as well. After identifying a tree that has woodborers, an inspector can do another kind of test or visual inspection to determine the type of beetle. So in an operational sense, the initial use of the detector will be as a screening tool. This will cut down on time because current screenings are time- and labor-intensive. A tree-climber takes hours to inspect a tree. With the detector, a single computer device can have leads to different trees, about 6 trees at a time.

One of the things we need to work out is a sampling scheme. How often do the beetles feed, the periodicity of feeding? That will determine how long we’ll need to sample each tree with the detector.

How long will it take for the detector to be operational?

One year. A lot of work will be done this year. We are using the system in the quarantine lab to detect beetles. We took the detector to China as well. Experiments are currently underway for fine-tuning the detector, and more experiments are planned for the coming year. While we’re working, Oak Ridge is improving the design of the instrument and algorithm. Both sides have another year of work to do.

What’s the current status of the beetle?

A new site was found in Chicago, near O’Hare airport, this year. It was near the incinerator site where tree cuttings were brought. The beetles probably escaped from materials brought there before the quarantine was imposed, about 6 to 7 years ago. 20 to 25 trees in that area have been affected. Chicago is currently keeping the beetle contained. Since 1998, 1,400 trees have been cut in Chicago. In New York, new little spots and new trees are found each year. It’s been steady. Over 5,000 trees have been cut in New York since the summer of 1996.

Is there concern that the beetles will get into forested areas?

Yes. In New York, Central Park is just a few blocks away from some infestations. In Chicago, All Saints Cemetery has a park-like setting where a few beetles were found. Lincoln Park is also a concern.

How do the beetles disperse?

They fly. They’re capable of flying a couple of miles. In the field, the beetles emerge from the branch of a tree. They tend to feed, mate, and lay eggs on the same or neighboring tree. There is typically no long-distance dispersal.

What kind of measures are being developed to destroy the beetle?

The beetles are being targeted using pesticides. Systemic insecticides are translocated through a tree using injectable techniques. An insecticide injection is a pressurized bottle with a straw or tube stuck into a hole in the tree. The insecticide gets into the tree. A couple of insecticides have been tested in the U.S. and China. In the U.S., the tree is injected and test samples sent to the lab. Samples are given to the Asian Longhorn Beetle at various lifestages. In China, we make cages with bugs on the trees, to see how they react to the insecticide injected into the trees. We also cut down some of the trees to check the mortality rates of larvae inside the tree.

People at the USDA-ARS (Agriculture Research Service) and APHIS (Animal and Plant Health Inspection Service) are also working on insect control. ARS is looking at biological controls. Investigations are also being done for tree species resistant to the bugs, that can be used for replanting. For solid wood packing material, new wood treatments are being studied for fumigation, or kiln-dried wood. Indicators are needed that will prove that the wood has been treated. methyl bromide, a fumigant, has been found to be an environmental hazard. So far, no substitutes have been found for it. One type of treatment being studied is microwave treatment.

Pheromone traps are also being investigated but there hasn’t been much luck so far in identifying long range pheromones. The Asian Longhorn Beetle probably has close range or contact pheromones, detected by the males using their antennae to touch females. There’s lots of areas of research into these various issues.