This paper was written as part of the 2004 Alaska Ocean Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.

Spruce Bark Beetles

Authors

Katie Rea
Jennifer Bartolowits
Madison Moe
John Chihuly

Team Coelacanth
Ninilchik School
PO Box 39010
Ninilchik, AK 99639

Table of Contents

1. Life history of the Spruce Bark Beetle
2. History on the Kenai Peninsula
3. What's Being Done Now
4. Effects of the Spruce Bark Beetles
5. Our Solution
6. Illustrations and Figures
7. Bibliography

Life History

Dendroctonus rufipennis is the scientific name of the significant natural agent of the mature spruce bark beetle. Out breaks from Alaska to Arizona have occurred in every forest with substantial spruce stands; losing 33 to 555 million boards of feet annually according to Dr. Ed Holsten, a U.S. Forest Service Entomologist. The spruce bark beetle attacks the living tree by making a hold in the bark, and eating the phloem tissue. The phloem is the tree's living tissue and is how food is made in the needles and then sent down to the sent down to the root system. The phloem layer is found right underneath the bark.

Trees become susceptible to damage by spruce beetle when they become mature and rot sets in. This puts stress on the tree and lowers its resistance to attack. Because the trees are rotting from within they can not stand up to high winds and are likely to fall down. These two factors allow spruce bark beetles to build their nests in spruce trees and to spread their population to even larger areas.

It takes more than one beetle attack to destroy a tree. When beetle population are low the trees can resist an attack, when the beetle attacks in mass, they can over come a tree. They do this by making holes on the main stem of the tree. These holes are about one millimeter in diameter. The beetles bore little tunnels called galleries in which they the phloem tissue. The trees fight attacks by producing extra sap, pushing them out of the tree. This fills up the galleries and which will then drown the invading beetles. This is called "pitching out." Older trees are not able to produce the extra sap necessary to do this.

The eggs of the spruce bark beetle are oblong in shape and whitish in color. The female beetle lays its eggs in groups on each side of a tunnel or gallery. The eggs then hatch into larval that are white in color and feed on the phloem tissue of the tree. The larval pass through the stages called instars. A spruce bark beetle life cycle in warmer climates and lower elevation can be one year where as in shady spots, higher elevation it can take up to three years. On average it takes two years from a spruce bark beetle to complete its life cycle. The larval moves out from the egg galleries and feed together as a group during their first and second larval stages. During their third and four instars they make their own feeding tubes and break away from the group. The larvae stage occurs during the first winter. During the second winter new adults emerge. They move to the base of the tree and bore into the bark to hibernate. By wintering at the bottom of the tree the beetle is less likely to be exposed to extreme cold or be sought after by woodpeckers. After two years the adult beetles come out of their host tree, in search of new host tissue. (http://www.habitat.adfg.state.ak.us/geninfo/kbrr/coolkbayinfo/kbec_cd/html/ecosys/terrest/barkbeet.htm)

History on the Kenai Peninsula

Alaska's Kenai Peninsula is a lush, fertile, green wilderness with a once vast area of beautiful trees. An unusual and large out break in 1996 killed an estimated 30 million trees. The unseen villain has always existed naturally but was never able to live long due to Alaska's harsh winters. The small culprit as an adult is no more than 6mm long but is responsible for the mass killings of mature and over mature trees. According to Dr. Ed Holsten, a U.S. Forest Service scientist, vast swarms of beetles emerged in 1997 towards the end of May which is normally many weeks earlier than usual. The numbers were greatly increased by the beetle's ability to complete their life cycle from egg to adult within one year. Before then, the spruce bark beetle had a usual two year cycle. This major change in the beetle's life cycle can only be caused by major warming temperatures which are caused by the burning of fossil fuels such as oil, coal, and gas. The bark beetle struck fast and might have been brought under control if simple things like harvesting diseased trees and using controlled burns to clear large infected areas had been utilized. It is estimated now that the Kenai Peninsula alone has over three million acres of forest devastated by the spruce bark beetle (Table 1). The forests are very unlikely to recover for many centuries, if ever, with the mortality rate being 100 percent. The plague to the Kenai's beautiful forests is part of a natural cycle and is slowly cycling down. Steps are now being taken but progress is slow and federal agencies have yet to act on lands held as National Forests and Wildlife Refuges. The National Park Service and U.S. Fish and Wildlife Service have also left dead and infected trees standing. In fact, approximately 1.9 million acres of infected forest have been unmanaged allowing them to become a terrible fire hazard (Figure 1). The matter is unavoidable and has even been recognized by former Alaska Senator Frank Murkowski (now Governor of the State of Alaska) who urged federal agencies to do a better job of coordinating their efforts to fight the beetle's outbreak and its aftermath on the Kenai. Things like planting 1.5 million seedlings over the past five years paid for by timber sales programs have helped rebuild the Kenai's forests but this is still a work in progress.

The fact is stated plain and simple. We have a mess on the Kenai Peninsula. The outcome to the way we act to this disaster will shape the future, not only on the Kenai, but statewide. We must start and continue to act before our trees are gone due to the spruce bark beetle. (http://www.fs.fed.us/r10/chugach/)

What's Being Done Now

Bark beetle management has thus far concentrated on regulatory salvage timber losses as they occur. This approach may help to regain immediate damage, but is expensive and costly. Individuals and homeowners can protect their own trees and land by spraying pesticides or plant a variety of trees at varying ages to repel mass attacks. Scientists are also working on developing time/temperature-release bubble membranes containing a synthetic anti-aggregate pheromone. Natural methods, that the tree performs itself, include defensive allochemicals, hypersensitive reactions, and developing impermeable barriers.

Anti-aggregation pheromones are important pieces in pest management that function by signaling incoming beetles that a potential host tree is too crowded. Anti-aggregation pheromones have been extremely effective where mass attacks are likely. Anti-aggregation pheromones are used as a means of avoiding overcrowding in the host tree. (http://www.pherotech.com)

They are known in bark beetles that use mass attack as a means of overcoming a host tree's defenses. This is best known in the genera Dendroctonus, Scolytus and Ips.

The use of anti-aggregation pheromones should be used as only one component of a management program. Infested trees should be removed and taken off site. The slash is a refuge for bark beetles, allowing them to breed, and possibly colonize nearby healthy trees. Thinning stands is a good preventative measure, however, it is not recommended during outbreak conditions. The disruption caused by the removal may cause stress in the remaining trees and expose them to bark beetle colonization.

A beetle-attacked tree responds in a number of ways. It may flood the invading beetles with pitch and oleoresins, defensive allochemicals. As the beetles bore into the tree, they cut resin ducts in the bark. These ducts drain their contents on top of the beetles. If the tree is vigorous enough, and the number of attacking beetles small enough, it will have sufficient oleoresin reserves to "pitch out" the attacking beetles. If the tree is not vigorous, and does not possess sufficient oleoresin reserves, the beetles will gain entry. If the beetles do gain entry, the tree can respond with a defense mechanism called the hypersensitive reaction. In this event, the tree tissue around the point of entry dies, and is flooded with tree resins and phenolics, which are produced by the surrounding cells. This cuts off the supply of food for the advancing fungal cells, and floods the area with chemicals that are toxic to bark beetles and that inhibit fungal growth. This process can exterminate the beetles and isolate and kill the fungus.

However, the synthesis of these defensive chemicals is an enormous drain on the tree's stored energy resources, and is very dependent on the level of carbohydrate reserves within the plant. The third level of defense becomes active in combination with the hypersensitive reaction. The tree tissue around the beetle and fungus attack site is modified to become impervious and hence form a barrier against further spread of the infection. Thus the tree actively isolates and seals off the dead cells and diseased tissues from the healthy portions of the tree. These barriers must be built quickly, or the fungus can break out of the reaction zones.

All three of these defenses necessitate that the tree have enough resources to overwhelm the attack effectively. Although very severe attacks will kill almost any tree, healthy trees can generally overcome moderate beetle attacks. (http://ag.arizona.edu/extension/fh/bb_faq.html)

Effects of Spruce Bark Beetles

The effect that spruce bark beetles are having on the Kenai River is more then what we think. By taking away the trees from around the banks of the river it will cause animals which utilize the marine ecosystem for food, but live in the trees to lose their habitats. Animals that lose their homes and have no other place to go will die off. The loss of our wildlife from around the Kenai River will cause long-term effects to their surrounding areas.

Bank erosion is another effect that is caused by the spruce bark beetle. This takes place by the lack of root systems after the trees die. Erosion of the banks can destroy not only aquatic life, but also destroy the nesting areas of many other animals. Killing the wildlife that nest near or on the banks of our local water systems will drastically affect the ecosystem on or around the Kenai River. The erosion could then bring other hazards such as: chemicals that can get into the water system, heavy debris that can damage many things down river that can have a negative outcome on the water system as well. By banks eroding it will also cause damage to the delicate riparian zones. Riparian zones help retain floodwater after heavy rains or snowmelts. These streamside wetlands mimic huge sponges absorbing and filtering water, which reduces peak flow levels in streams, and replenishes the groundwater that helps maintain lake levels and stream flows. As runoff water moves through trees and other plants, leaves and twigs, it slows and drops sediment that has been carried along. Since these sediments are deposited on the banks rather than in the streams, floods can actually be bank-building events. This settling process also keeps nutrients from flowing into streams and lakes, permitting plant roots to take up the nutrients that have dissolved in the runoff and soaked into the soil, reducing the amount of pollution flowing into lakes and streams. Because the soil is exceptionally fertile, riparian areas can produce stands of very large trees. But because of the crucial functions these trees serve, riparian areas are not suitable for logging. These areas are sensitive to other activities and disturbances as well: excessive livestock grazing, agriculture, road-building, urban development, and recreation. By damaging this zone, it will cause all the marine life that live within it, to day or be stressed out. It is a chain reaction; first you damage the zone, then the animals are stressed or dead, which can then cause the other bigger animals that feed on them to become deprived of their food source.

By taking out the trees it will then take away the shade from the water in the Kenai River, without shade the water will heat up because there is no protection from the sun. The hotter the water is the less oxygen it can hold within. Without a sufficient supply of oxygen the lacustrine ecosystem can't survive efficiently. Additionally, by removing the trees and leaving open land that can produce thick grass to come up in the place of those missing trees, even though the stumps are still there. The grass can then overpower the water and cause it to deplete by sucking up all the water with its roots.

After the spruce bark beetles have killed the trees there becomes no protection for the ground beneath it. During the winter seasons all the snow will collect on the ground, instead of some of it being collected on the branches. Then when it comes time for break-up all the snow that accumulated underneath the tree will all melt at the same time, because there will be no shade to hide it from the sun. Causing all the melted snow to go into the water and initiate spring floods. (Mike Fastabend, Kenai Peninsula Borough Spruce Bark Beetle office)

It may take years for spruce bark beetles to kill a spruce tree. Before the tree dies, it attempts a counterattack. The tree produces chemicals, called terpenes that are supposed to drive the beetles off. Sometimes it works. The spruce bark beetles have developed not just a resistance to terpenes, but in some cases terpenes are an attractant to the spruce bark beetle. The spruce bark beetle has developed a means of sensing some of the terpenes and using it as a homing beacon to find trees that are under attack or under stress. As the trees decay, the terpenes wash into the rivers, lakes, and coastal waters where they may be toxic to salmon and other fish. Another concern is that the terpenes are being bioderived into other compounds through metabolism within bacteria in the water. Bacteria actually convert these compounds into other compounds. There is evidence that these other compounds may be more toxic than the terpenes they were derived from. The bacteria are to some extent contributing to the potential for toxicity.

It may take years for spruce bark beetles to kill a spruce tree. Before the tree dies, it attempts a counterattack. The tree produces chemicals, called terpenes that are supposed to drive the beetles off. Sometimes it works. The spruce bark beetles have developed not just a resistance to terpenes, but in some cases terpenes are an attractant to the spruce bark beetle. The spruce bark beetle has developed a means of sensing some of the terpenes and using it as a homing beacon to find trees that are under attack or under stress. As the trees decay, the terpenes wash into the rivers, lakes, and coastal waters where they may be toxic to salmon and other fish. Another concern is that the terpenes are being bioderived into other compounds through metabolism within bacteria in the water. Bacteria actually convert these compounds into other compounds. There is evidence that these other compounds may be more toxic than the terpenes they were derived from. The bacteria are to some extent contributing to the potential for toxicity.

Our Solution

Our solution for reversing and decreasing the negative effects of the spruce bark beetle is logging the dead and infected spruce trees, the use of trap trees, and waiting for the beetle's natural cycle to end.

Logging around the banks of the Kenai River will reduce the available host trees that could later contaminate the water. Dead trees that can fall into the river will cause disturbances in the river bed lifestyle, and cause greater bank erosion. By logging the trees and leaving the stumps shorter than eighteen inches this keeps the root system intact preventing further bank erosion. By logging around the Kenai River banks it will make it more beneficial to the marine ecosystem, it would then be easier to do around the banks instead of doing the whole peninsula.

Trap trees placed in the central Kenai Peninsula forests will attract ten times the number of spruce bark beetles than a untreated live tree. This happens because the trees used as trap trees have a diameter greater than twelve inches at breast height. They cut the live uninfected trees down and spray the bark with insecticides that attract beetles. Another is to remove a uncontaminated spruce bark tree is cut the tree and lay it down and wait for beetles to have lay their eggs, this is to avoid all the freshly laid eggs from hatching. The tree is then removed and disposed of. Ideally the trees would be laid down in the spring and eradicated from the location in December. This depletes the number of spruce bark beetles that can produce more larvae.

The natural cycle of the spruce bark beetle is coming to an end on the southern Kenai Peninsula. In four to five years we are hopefully going to see an end to the outbreak. Unfortunately, we still have ten more years to go on the central Peninsula. We should focus more on the central Peninsula because there is more possibility for the outbreak to damage the marine ecosystem.

Funding our solution is getting a federal grant from the United States Department of Agriculture for approximately 2.2 million dollars. The likelihood of receiving a grant suitable for our solution is high. This department is the country's largest conservation agency, which encourages voluntary efforts to protect soil, water, and wildlife on the 70 percent of America's lands that are in private hands.

We believe that by trying to solve this problem it will add jobs to the local communities. There will be workers need to run machinery, office work, make trap trees, and more. There aren't many solutions to the current problem with the spruce bark beetle; there are plenty of people still trying to figure out more efficient ways to solve the damages from the spruce bark beetle. The best thing is to wait for the cycle to die down and then get the beetle to stay at a low percentage rate instead of cycling back up. We imagine that the previous ideas mentioned can help benefit the Kenai River and help prevent further damage.

Illustrations

Illustration 1.

Adult spruce beetle

Illustration 2.

Larvae eggs

Illustration 3.

Evidence of the spruce bark beetle on the Kenai Peninsula.

Illustration 4.

Dead trees, with live ones in the background.

Illustration 5.

A beetle gallery.

Illustration 6.

Fallen, dead trees, killed by the beetle.

Illustration 7.

Riparian zone of the Kenai River.

Illustration 8.

Spruce tree killed by the deadly beetle.

Illustration 9.

Trap trees fallen to kill emerging spruce bark beetles.

Table 1.

Figure 1.

Bibliography

Mike Fastabend, Kenai Peninsula Spruce Bark Beetle office 36130 Kenai Spur Highway, Soldotna, AK 99610 (907)260-6202

Phero Tech Inc. http://www.pherotech.com Delta British Columbia, Canada (604)940-9944

Arizona Forest Health. http://cals.arizona.edu/extension/fh/bb_faq.html (928)337-2267

Dalrymple, Byron. The Sportsman's Guide to Game Fish. New York, NY: The World Publishing Co., 1968. 480 pgs.

Erik Leslie and Tom Brady, Silva Ecosystem Consultants Ltd. http://www.silvafor.org/publications/library/docs/DougFirBarkReview.pdf

Coowe Moss-Walker, Alaska Department of Fish and Game (907)465-4100 http://www.habitat.adfg.state.ak.us/geninfo/kbrr/coolkbayinfo/kbec_cd/html/ecosys/terrest/barkbeet.htm

Chugach National Forestry. http://www.fs.fed.us/r10/chugach/ (907)743-9500

Dr. Bob Wheeler- Forestry Extension Specialist www.uaf.edu/seagrant/news/00ASJ/03.06.00_ToxicSpruce.html

Robert Carillio. http://www.nanfa.org/education/carillio/riparian.htm http://www.borough.kenai.ak.us/sprucebeetle/default.htm

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