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Forestry Report R8-FR 55 - January 1995
Written by:
Jane Leslie Hayes, Southern Research Station 2500 Shreveport Highway, Pineville, LA 71360
and James Meeker, Florida Department of Agriculture, 1911 Southwest 34th Street,
Gainesville, FL 32608-1201
A promising breakthrough in controlling the damage done by the southern pine beetle
(SPB), Dedroctonus frontalis in urban and rural areas has occurred as a result of research
by the USDA Forest Service (Jane L. Hayes, Brian L. Strom, and Lary Roton) and Mississippi
State University Forest Products Laboratory (Leonard L. Ingram, Jr.). A patent has been
issued jointly to the Forest Service and Mississippi State University on the use of a
natural compound, 4-allylanisole (4-AA), that is a repellent to the SPB (Hayes and others
1995).
The SPB is one of the most destructive insects of pine trees in the southern United
States. The common signs of SPB infestation dying, yellow, or red-crowns of infested
trees- are occurring in urban areas as the SPB forages across forest lines. This small
insect (less than half the size of a grain of rice) and its near relatives are capable of
killing all species of pines grown in the South.
The female SPB initiates the attack on the tree by boring through the bark. During this
process she secretes a chemical substance that attracts other beetles of both sexes to the
tree in mass. These beetles bore into the host pine and begin to reproduce. As the beetles
and their offspring bore, they typically introduce a bluestain fungus into the tree. This
combination of boring by the beetles and proliferation of the bluestain fungi ultimately
causes tree mortality. When bark beetle populations are low, trees under some
physiological stress, such as those struck by lightning, wounded, or wind storm damaged,
appear to be most vulnerable. When bark beetle populations are high, even healthy trees
may die from the mass attack of beetles.
SOUTHERN PINE BEETLE IN URBAN AREAS
Pines in urban areas are as vulnerable to SPB as they are to lightning strikes. In
fact, beetle infestations often occur after lightning strikes. A general rule of
thumb is that "if the lightning does not kill the tree, the beetles attracted
to it probably will." Generally there are no data on pine loss in urban areas. A call
to private tree contractors in Pineville, LA, where bark beetles typically occur in the
urban environment, suggests that each removes from 30 to 40 pine trees from residences
annually because of lightning strikes and/or beetle infestations, at an average cost of
approximately $250 per tree.
Infestation by bark beetles is also associated with site disturbance and wounding that
may occur during construction projects or landscaping work (such as pruning). Under any of
these circumstances 4-AA may provide an environmentally neutral means of providing some
protection from SPB infestation in urban areas. Once the threat of infestation has
subsided, treatment can be immediately ceased. While no nonlethal material can be expected
to provide 100 percent protection, 4-AA has the potential to significantly lower the risk
of bark beetle infestation in urban habitats.
NEW ADVANCES IN PINE BEETLE MANAGEMENT FOR URBAN AREAS
Lindane and chlorpyrifos are two traditional chemical pesticides registered for use
to protect pine trees in urban areas from SPB. These pesticides are generally applied with
a hi-pressure hose to the tree trunk. Lindane provides protection for 3 to 6 months.
Chlorpyrifos has a slightly shorter length of effectiveness and may need to be reapplied
at intervals of 2 to 4 months. There are serious concerns about environmental
contamination related to the use of these insecticides, such as how they impact beneficial
organisms.
Particularly in the last decade. the forestry research community has intensified its
efforts to develop technology as an alternative to pesticide use. One of the most
promising areas in bark beetle research is the use of the insect's own communication signals
(pheromones) to disrupt or inhibit infestation growth. A pheromone is a physical or
behavioral chemical signal that is secreted by individuals of the same species. The SPB
females produce a pheromone during the initial stages of colonization that attracts other
SPB of both sexes. The SPB males produce "inhibitor" pheromones that signal that
the host tree under attack is fully colonized. This signal causes the beetles to spillover
to nearby trees, which results in spreading the growth of the infestation. Verbenone, the
primary inhibitory pheromone produced by SPB, is being used effectively to disrupt spot
growth under some conditions. (Payne and billings 1989).
Another promising chemical, 4-AA, found in small quantities in the oleoresin (sap or
pitch) of many pines, has repellent properties to many species of conifer-feeding bark
beetles (Hayes and others 1994a; Hayes and others 1994b; Hayes and Strom 1994). In
laboratory and field studies, > 80% of SPB were repelled by the presence of this
chemical and natural enemies of SPB do not seem to be affected by 4-AA. Four-allylanisole
has been very effective as a tree protectant in practical tests.
SOUTHERN PINE BEETLE OUTBREAK IN GAINESVILLE, FL
In 1992, two pines that were struck by lightening in a residential area were treated
with 4-AA. Treatment consists of placing nine 20-milliliter polyethylene vials equipped
with cotton wicks at 1-meter (1.1 yard) intervals on the damaged side of the tree trunk,
from ground level up to 8 meters (8.7 yards). In both cases, the treated trees were not
attacked by SPB for the 30 days of 4-AA treatment. These results encouraged us to consider
the use of 4-AA in urban areas to protect urban trees from SPB attack.
During 1994, an unprecedented and intense SPB outbreak occurred throughout a
60-square-mile area of greater Gainesville. This outbreak killed over 18,000 pines
(primarily loblolloy) and impacted more than 350 public and private landowners. The
community, under the direction of the Florida Division of Forestry and with Federal
assistance, fought this freak outbreak aggressively, attempting to remove all infested
trees and in many cases treating uninfested trees with registered materials for protection
(lindane. and chlorpyrifos).
On a small-scale voluntary basis, five homeowners allowed us to treat their uninfested
trees (73 trees) with 4-AA. In addition, two infestations in conventional pine stands were
treated. Virtually all untreated trees in the vicinity of the active SPB infestations were
attacked. However, all three materials (lindane, chlorpyrifos, and 4-AA) provided good
protection (> 90 %) from attack by SPB. In these tests, 4-AA provided homeowners with
an environmentally-neutral alternative to chemical pesticide application for SPB
protection of trees in their neighborhood. Excluding labor, the 4-AA treatment cost per
tree in the Gainesville test was around $30 for 3 months of protection. At the time of
this study, application techniques for using 4-AA include the use of climbing ladders
during initial setup, followed by refilling of vials about once per month, depending on
weather conditions. Because protection is often a long-term proposition, slow-release
devices that can be installed without climbing and that last for 60 to 90 days are
desirable. We are currently using a new sealed, gel-filled vial(developed in cooperation
with Phero-Tech, Inc) which lasts for over 120 days. Further work is ongoing to develop
effective, efficient, and economical application systems.
FUTURE AVAILABILITY
Large-scale testing (up to 250 acres) of 4-AA will be conducted in the future.
Development of improved dispensers, application technology, as well as
licensing-agreement negotiations are under way. Thus steps toward registration and
eventual commercialization are hopefully on the fast track. Extensive toxicity tests have
yet to be done. However, because the projected use of 4-AA is limited to deterrence or
inhibition, it is unlikely that doses high enough to cause toxic reaction would be used.
Areas that need to be explored further include the possibility of SPB becoming resistant
to 4-AA and the negative consequences of redistribution of beetles through deterrence.
REFERENCES
Hayes, J.L.; Ingram, L.L.; Strom, B.L.; Roton, L.M.; Boyette, M.W.; and Walsh, M.T.:
1994a Identification of a host compound and its practical applications: 4-allylanisole as
a bark beetle repellent. In: Proceedings, 4th Southern Station Sciences Meeting, February
1-2, 1994, Starkville, MS. General Technical Report S0-104. USDA Forest Service, Southern
Station Experiment Station. New Orleans, LA: 69-79.
Hayes, J.L.,and Strom, B.L. 1994. 4-Allylanisole as an inhibitor of bark beetle (Coleoptera:
Scolytidae) aggregation. Journal of Economic Entomology: 87(6) 1548-1556.
Hayes; J.L.; Strom, B.L.; Roton, L.;.and Ingram, L.L., Jr.1994b. Repellent properties
of a novel host compound to southern pine beetle. Journal of Chemical Ecology. 20(7):
1595-1615.
Hayes, J.L.; Strom, B.L.; Roton, L.; and Ingram, L.L. Jr., inventors: USDA Forest
Service and Mississippi State University, assignees. 1995. A repellent of bark beetles for
protection to conifers. U.S. patent 5,403,863. April 4.
Payne, T.L., and Billings, R.F. 1989. Evaluation of (S)-verbenone applications for
suppressing southern pine beetle (Coleoptera: Scolytidae). infestations. Journal of
Economic Entomology. 82(6): 1702-1708.
This bulletin is also available in an electronic format on the Southern Region Urban
Forestry home page: http://www.uga.edu/~soforext/
The United States Department of Agriculture (USDA) alternative means for communication
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complaint, write the Secretary of Agriculture, U.S. Department of Agriculture, Washington,
DC 20250, or call (202) 720-7327 (voice) or (202) 720-1127 (TDD). USDA is an equal
employment opportunity employer. Please call 706/546-3203 for more information on the
Technology Bulletins.
Forestry Report R8-FR 55 January 1996
USDA FOREST SERVICE/SOUTHERN REGION, 1720 PEACHTREE RD., NW ATLANTA, GA 30367, SOUTHERN
RESEARCH STATION, 320 GREEN STREET, ATHENS, GA 30602
Printed on recycled paper.
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