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An incredible life cycle: What does the Asian longhorned beetle look like as it grows inside a tree?
The Asian longhorned beetle (Anoplophora glabripennis), commonly known as the star bug or ALB, is native to Korea and certain areas of China. The insect was first discovered in the eastern United States in 1996 and has since spread to Canada and some European countries as trade has expanded. So what exactly is the growth process of this not-yet-fully-understood beetle inside a tree?
The beginning of the life cycle
An adult female Asian longhorned beetle lays 45 to 62 eggs in her lifetime, which are deposited beneath the bark of a tree, usually in the phloem, through small pits created by chewing through the bark.
The incubation period for the eggs depends on the ambient temperature and is usually between 13 and 54 days. When the eggs are laid in the fall or winter, they go dormant until the larvae hatch in the spring of the following year.
Larva Stage
The hatched larvae are cylindrical and elongated, grow to 50 mm long, and dig feeding tunnels in the phloem of the tree. As the larvae develop, they tunnel further into the heartwood of the tree. The larvae molt at least five times over the course of one to two years, and the process of emerging from the shell is usually complete in the spring, when the larvae pupate at the end of the tunnel.
Life cycle of adult insects
After emerging from their nests, adults begin looking for mates and laying eggs, usually on the trees where they grow.
Adult nutrition on a tree depends on the tree's health, and once the crown of a tree begins to die back, the beetles will gradually move toward the trunk. Although their flight capabilities are limited, under the right conditions adults are able to move distances of up to 2.5 km when searching for a new host.
Ecosystem violations and economic crisis
As the larvae are extremely harmful to trees, the Asian long-horned beetle has been listed as an invasive species, posing a serious threat to forest and urban ecology. Research in the United States shows that the beetle has the potential to destroy up to 30.3% of urban trees, causing an estimated economic loss of up to $669 billion.
Monitoring and management measures
Recording and inspecting the exit holes on trees is an important task in order to effectively monitor the spread of the Asian longhorned beetle pest.
The presence of exit holes 1 to 2 centimeters in diameter in trees, along with resin or sawdust, are clear signs of a beetle infestation. In addition, using traps to catch adult insects and training dogs to sniff wood chips are common monitoring methods.
Salvage measures and biological control
Regulations and measures against the beetle were followed up accordingly, and affected trees were sealed. Of course, professional tree care workers will play an important role in ensuring that infected trees are safely removed and properly disposed of.
Understanding and Prevention
In addition to regular inspections and periodic authorized operations, strategies for tree improvement and biological control are also beginning to be considered.
For example, using tree species that promote full wood to improve resistance, and introducing natural enemies such as bark woodpeckers to combat the Asian longhorned beetle.
ConclusionThe fight to save the Asian longhorned beetle continues, but as global climate change and trade grow, the ability to effectively control this invasive species and its life cycle will have profound impacts on our forest ecosystems. In the future, in addition to strengthening relevant management and control, can we explore more effective biological control methods to prevent this threat?
