OAK RIDGE, Tenn., Oct. 27, 2000 -- An invasion of tree-destroying Asian Longhorned Beetles could be slowed or perhaps stopped with a larvae detection system being developed by researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL).
Larvae from the beetles, which are native to China and Korea, are inadvertently imported into the United States nestled inside the wood of shipping crates containing a host of products. Within days of their arrival, beetles are out boring into trees, where they lay eggs. The larvae start eating the tree's cambium, the layer that generates new cells, disrupting its nutrient-transporting vessels. Eventually, the trees die. It's a problem that has a lot of people concerned.
"These beetles, which grow to more than an inch in length, can cause billions of dollars in damage to forests and to the maple syrup, lumber and tourism industries," said Cyrus Smith of ORNL's Instrumentation and Controls (I&C) Division.
In the U.S., the beetles' favorite targets are maples, horsechestnuts, black locusts, elms, birches, willows and poplars. Already, they have infested thousands of trees in New York and Chicago. The only effective means to eliminate the beetle is to cut infested trees and destroy them by chipping or burning.
Visual inspection of crates and trees is difficult and ineffective, so Smith and colleagues at ORNL are developing a hand-held instrument that identifies the vibrations made by the larvae as they feed on the wood. Their goal is to develop an instrument that can distinguish the Asian Longhorned Beetle larvae from other insects and identify the larvae at different stages of maturity.
To develop the instrument, Smith, Glenn Allgood and Dale Treece, also of the I&C Division, are gathering vibration data from these beetles and other insects as they feed. Researchers are analyzing the information and developing algorithms -- mathematical solutions to solve complex problems -- to help identify the presence of telltale characteristics.
"We'll then incorporate these algorithms into a prototype instrument that can detect the bugs and determine if the infestation is by the Asian Longhorned Beetle," Smith said.
Initial results gained with acoustic sensors and a laptop computer loaded with the algorithms are encouraging.
"Our algorithms have been successful in detecting larvae in sample logs and in trees in natural settings," Smith said, "but we still need to analyze data from various larvae stages, different woods and different insects to see if our algorithms can discriminate these effects."
Researchers have discovered that because young larvae feed at the wood-bark interface, where the material is softer, the vibrations are smaller in amplitude. Older larvae feed on the interior wood and produce larger amplitude vibrations, which are easier to detect. This is significant and should help in detecting larvae at ports of entry because crating material is made from interior wood that contains more mature larvae.
Once the operation and accuracy of the prototype instrument have been documented in the field, the technology will be transferred to an industrial partner for commercialization and miniaturization.
ORNL is a DOE multiprogram facility operated by UT-Battelle. The project is funded by the Department of Agriculture's Forest Service North Central Research Station in East Lansing, Mich.
Materials provided by Oak Ridge National Laboratory. Note: Content may be edited for style and length.
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