|
 The genus and species for the Southern Pine Beetle (SPB)
is Dendroctonus
frontalis, which means “tree killer.”
The SPB is a tiny insect--about the size of a grain of rice. When the SPBs attack in large numbers, they can kill even vigorous pine
trees. This is because the
beetles can disperse widely and reproduce rapidly.
|
 The life cycle of the SPB is an example of complete
metamorphosis. The cycle begins
with eggs that hatch into larvae within one week.
The larvae develop in two weeks and then enter the pupal stage.
The beetle emerges in one week.
The female beetle may live one month and lay about 160 eggs.
A good resource for more information on metamorphosis:
http://www.uky.edu/Agriculture/Entomology/ythfacts/4h/unit2/metavari.htm
|
  Females beetles initiate attacks on the trees.
After the beetles arrive at a tree, they produce a substance called
pheromone which attract other beetles.
Parents emerge in one week to disperse and infest additional pines.
Beetles produced from the eggs laid by these parent beetles emerge in
four to six weeks and disperse to infest new pines.
|
 There are three major groups of beetles that attack:
the immigrant adults, reemerging parent adults, and the newly emerged
brood adults. Swarms
of beetles can kill even healthy pines. Pines,
which have been weakened for some reason i.e. damage due to ice storms, are even
more susceptible to beetle invasion. These
trees cannot produce enough resin or pitch to help rid the tree of the beetles. |
 There are several very distinctive signs to identify the
attack on the pine trees.
 The pine
trees produce popcorn-like pitch tubes on their trunks in an effort to
“pitch” the beetles out of the tree.
The
beetles bore one-millimeter holes in the bark.
If the bark is pulled back, a serpentine of egg galleries made by the adult
beetle can be found in the inner bark.  The
pine needles change from dark green to light green, to yellow, to red, and then
fall to the ground. A chart of
symptoms associated with various stages of the SPB-attacked trees may be found
in a publication of Renewable Resource Notes entitled, “The Southern Pine
Beetle.” An electronic copy is
located at the following URL: http://www.utextension.utk.edu/publication/forestry.htm
|
 The beetle tunneling in the inner bark effectively girdles
the tree, which leads to the death of the tree. Not only do trees suffer from the beetle attacks,  but also
from the blue-stain fungus that is carried into the tree by the beetle.
This fungus colonizes fluid-conducting tissues in the tree and disrupts
the flow of the sap and water between the top of the tree and the roots.
|
|
  Several factors contribute to the outbreaks of SPB.
Among these conditions are weather, population dynamics, forest
conditions, and landscape structure. Other factors affect how many beetles can attack in one
day. Among these factors are
the distance to the surrounding pine trees, the health of the trees,
tree and beetles-produced attractants as well as repellents, and the
weather. Many beetles may emerge
and due to unfavorable conditions not be able to attack another tree.
|
 The destruction of the pine forests in Tennessee has
devastating affects on the environment and the economy of the area.
The environment is affected by the change in the forest composition, the
fire hazard that is produced, and the destruction of exiting wildlife habitats.
The economy has been affected as many of the small lu mber companies and
sawmills are no longer in business. Large
lumber companies are adjusting their management plans and have increased cost as
they try to control the beetle destruction.
Many private landowners lost thousands of dollars because they were not
able to harvest their trees before the beetle infested them. Because of the potential destruction, it is important to
control the SPB. There are several
methods that may be used: cut and
remove infested trees; cut and spray trees with approved insecticide; and cut
and leave. |
