Winter of 2015 has been one of the hottest
winters on record for a significant portion of northern United States (1). The warmer winter is
likely a result of the increase in climate change caused by the emission of
carbon dioxide into the atmosphere. As a
result from the warm winter, beetles have not been killed from the cold and
have traveled north into Canada (1, 2). Similarly, beetles are attacking forests
worldwide such as Poland, China, and Nepal (3,
4, 5). Beetles pose a significant threat to forests
due to several forests dying off causing a huge environmental impact. Beetles are a serious threat to the forest
ecology because some of them are highly invasive while others are overfeeding
due to densely packed forests and warmer conditions.
Beetles are a severe problem for forests worldwide. Beetles feed on the resins beneath the tree’s
bark, which is one of the tree’s first defenses against predators, and make
distinct S-shaped patterns below (2). If
the tree senses there are invaders, the tree will activate cell death, where
the beetle is burrowing, releasing a toxin (2, 5). In the meantime, the female beetle is
feasting and laying eggs beneath the bark (5).
Although the toxin is enough to kill the female beetle and her
offspring, if there are large swarms of beetles, the tree is certain to die
(2). Once the tree experiences death, the
eggs will hatch into the larvae and they will continue to burrow during the
winter until they grow to adulthood (5).
The cycle can then begin anew and infect several other trees,
effectively killing the forest. An
infestation can be called an epidemic when at least one percent of the total
growing population is afflicted (5). An
epidemic can easily wipe out an entire forest destroying both homes for several
animals and renewable resources for people.
Scientists have several explanations are to what is
fueling the beetle invasion. Firstly, warmer temperatures and humid conditions
have contributed to the increase of beetles (1, 2, 3, 4, 5). The forest density being overcrowded is also
lending for more trees to be infected (1, 2, 3, 4, 5). Overcrowding is when there are too many trees
all in a small amount of space which can allow for the transmission of disease
and especially beetles to ravage the forest.
Tree health and age are other factors that allows for trees to be more
susceptible (3, 4, 5). Aside from the
common explanations as noted above, “arid climate, strong winds, low rainfall,
sparse vegetation” and human interference have created favorable conditions for
species to survive and carry disease (4).
In addition, little attention has allowed the species to boom and
quickly extinguish forests (3, 4). A
lack of natural enemies for both native and invasive species has also
contributed to the tree death (5).
Mountain Pine Beetle
Source: http://media.graytvinc.com/
images/pine+beetle.png
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Invasive species have been a significant issue for
several forests. These species choke out
native species due to competition and a lack of predators. The southern pine beetle is an invasive
species that originated in southern United States (1). Typically, the northeastern winters have kept
the beetles at bay due to them not being able to survive a temperature of
negative eight
degrees Fahrenheit (1, 2). The beetles are closely related to the
mountain pine beetle, which is also destroying forests in northern United
States and even extending into Canada and the boreal forest (1, 2). The mountain pine beetle is native to the
United States but an invasive species for British Columbia. The beetle is slowing gnawing its way through the forests
and causing a great deal of damage to the timber industry in Canada (2). Since
the 1990s, approximately 60 million acres of British Columbian forest has been destroyed
by the mountain pine beetle (2).
Not
all beetles have been invasive. In fact,
a number of native species have drastically
Bird's eye view of Bialowieza Forest.
The browned
trees are attacked by beetles
Source: http://www.bialystok.lasy.gov.pl/image/
journal/article?img_id=28501307&t=1454674855574
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There are several proposed ideas in order to
remedy the beetle epidemic. Firstly, cutting down infected trees would prevent
the beetles from moving to another tree.
In addition, thinning the forest will reduce the amount of spaces the
beetles can spread to and less competition increase the health of the forest
(3, 5). China has suggested using biopesticides to control the beetles without
harming the forest and pheromones to deter the beetles from finding potential
trees (3).
Beetles are pose a
serious threat to the health of forests worldwide. The increase in temperature, humidity, and overcrowded
forests created conditions for beetles to thrive. In doing so, forests around the world are
declining. However, there are
conservation possibilities to control beetles from feasting on forests. Although there is a looming invasion for the
US, efforts are being made to save the forests.