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					                      PEST ALERT
       Redbay Ambrosia Beetle and Laurel Wilt Fungus

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, was first detected in the U.S. in a
survey trap near Port Wentworth, Georgia in 2002. This pest is not yet in Hillsborough
County, but may soon become a problem because of the way in which it can spread.
IDENTIFICATION: Xyleborus glabratus is a small, elongate, cylindrical beetle about 2 mm in
length. It is very similar in appearance to the dozen other members of the genus, both native
and exotic, already found in Florida.




BIOLOGY: Very little is known about the biology of Xyleborus glabratus at this time, but it is
probably similar to other species in the genus. X. glabratus does not actually feed on wood,
but instead, adults and larvae feed on fungi (a vascular laurel wilt pathogen, Ophiostoma sp.)
that are inoculated into galleries in the sapwood by the adult females.
MODE OF ACTION: X. glabratus bores into a host tree, carrying spores of the laurel wilt
fungus in specialized mouth cavities. The laurel wilt fungus colonizes in the galleries and
infests the xylem of the tree, preventing the transport of water and nutrients. The tree
undergoes drought stress and becomes an attractive host, which is then attacked in mass by
X. glabratus for reproduction of the beetle. The tree dies or is severely damaged, and new
beetles emerge to infest new trees.
COMMON HOSTS: Confirmed hosts in the U.S. at this time include redbay,
sassafras, and avocado.
HOST SYMPTOMS: Trees freshly attacked by Xyleborus glabratus exhibit
few external symptoms initially. Small strings of compacted sawdust may
protrude from the bark at the point of attack, but these strings disintegrate
easily and are not always readily apparent. Leaves will exhibit severe wilting,
and may turn brown while still on the tree. Pencil-sized boring holes may be
evident in the bark, and black or brown streaking will be visible just under the
bark. This streaking is an indication of the laurel wilt infestation.
MANAGEMENT: At this time there are no tested or proven treatments for prevention or
control of this insect and its associated pathogen. To avoid spreading the beetle and
pathogen to new areas, wood or chips from infested trees should not be transported out of
the local area where the trees were found. Infested trees cut in residential areas should be
chipped and left onsite as mulch, or disposed of as locally as possible. Firewood or wood for
turning should not be transported.
RESEARCH: Current research is being conducted by USDA, FDACS, UF/IFAS, and several
institutions in Georgia and South Carolina. Research topics include screening for resistance
in avocados, susceptibility of native and non-native Lauraceae, and control of the pathogen.
PRELIMINARY RESEARCH DATA:
   The redbay ambrosia beetles are attracted to volatiles naturally emitted by members of
    the Lauraceae family.
   Populations of the beetle increases in warmer temperatures (typically from June to
    October).
   All avocado cultivars are most likely susceptible to infestation.
   The larger the tree, the more susceptible it is to the laurel wilt fungus.
   The beetle may be more attracted to damaged (e.g. pruned) trees.
More information about the effect of the redbay ambrosia beetle and laurel wilt disease on
avocados:
Laurel Wilt: A Threat to Redbay, Avocado and Related Trees in Urban and Rural
Landscapes, http://edis.ifas.ufl.edu/HS391
Redbay Ambrosia Beetle-Laurel Wilt Pathogen: A Potential Major Problem for the
Florida Avocado Industry, http://edis.ifas.ufl.edu/HS379
Floridians are urged to report laurel wilt symptoms on avocado or redbay trees to the state
Division of Plant Industry at 1-888-397-1517. Symptoms include wilted stems and leaves,
black streaking in the wood, and strings of compacted sawdust protruding from tree trunks.
Instructions on how to collect and send samples to the Division of Plant Industry (DPI):
http://www.doacs.state.fl.us/pi/enpp/pathology/images/sample_collection_host_plant.pdf

				
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posted:9/10/2012
language:English
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