JULY 2002
SPB UPDATE
Information on southern pine beetle research and
management is jointly sponsored by the Forest Insect Research Project, Southern
Research Station, 2500 Shreveport Highway, Pineville, LA 71360, phone (318)
473-7232 and the Southern Region, Forest Health Protection, 1720 Peachtree
Road, Atlanta, GA 30309, phone (404) 347-2719.
www.srs.fs.fed.us/research/4501/
CURRENT CONDITIONS
Southern Pine Beetle South-wide Trend Predictions for 2002
by Ronald F. Billings (with data contributed by southern forest pest specialists)
(See
Survey
and Predictions for 2002)
The southern
pine beetle (SPB), Dendroctonus frontalis,
has a well-deserved reputation as the most destructive forest pest of pine
forests in the South. In 2000, nearly 60,000 multiple-tree infestations were
detected on federal, state and private forest lands throughout the South,
resulting in the loss of millions of dollars of resources. The Texas Forest
Service (TFS) has developed a reliable system for predicting infestation trends
(increasing, static, declining) and levels (low, moderate, high, outbreak) that
has been implemented across the South since 1986. This information provides
forest managers with valuable insight for better anticipating SPB outbreaks and
more lead time for scheduling detection flights and preparing suppression
programs.
Each spring, traps baited with the SPB attractant (frontalin) and southern pine
turpentine are set out in pine forests when dogwoods begin to bloom. Dogwood
blooms mark the primary dispersal season for populations of the destructive SPB
as well as certain beneficial insects. The traps are monitored weekly for a 4-6
week period by federal and state cooperators. Of particular value for
forecasting purposes are catches of clerids (also called checkered beetles),
known predators of SPB. Using data on the average number of SPB captured per
trap per day and the relative proportion of SPB to checkered beetles, infestation
trends for the current year can be forecasted (see related article
entitled “How to Forecast Southern Pine Beetle
Infestation Trends with Pheromone Traps”).
The results from the 2002 prediction survey indicate
increasing or continued high populations in South Carolina, Georgia, Florida,
and certain counties or ranger districts in Virginia and North Carolina. In fact, some of the highest trap catches
ever recorded since the SPB prediction
system was begun in 1986 were turned in by South Carolina, particularly in the
Piedmont region. Many SPB infestations
already have been detected in these Piedmont counties. Beetle activity is
predicted to be declining from last year's high levels in most areas surveyed
in Kentucky, Tennessee, and Alabama.
Mississippi and eastern Louisiana may see SPB increases from the low
levels these states experienced last year.
Very few or no SPB infestations are expected again this year in Texas,
Arkansas, Oklahoma, western parishes of Louisiana, and in Delaware, and
Maryland.
Annual predictions of infestation trends have proven to be 75-85% accurate.
Collectively, trend predictions from numerous specific locations provide
insight into SPB population shifts within a given state as well as across the
South. Also, comparison of trapping results for the current year with those
from the previous year for the same localities provides additional insight into
SPB population changes.
In general, average trap catches that exceed 30 SPB per day, especially those
in which SPB make up more than 35% of the total catch (of SPB and clerids), are
indicative of increasing or continued high SPB infestation levels in the
current year. Conversely, when catches of predators far outnumber those of SPB
and fewer than 20 SPB adults are caught per day, infestation trends are likely
to decline or remain at low levels. It is uncertain whether the predator
population is directly responsible for declines in SPB outbreaks. Most likely,
predators are just one of many contributing factors.
The South-wide SPB survey results and trend predictions will also be posted on
the Internet at http://www.fs.fed.us/research/4501/
. Appreciation is expressed to the many state and federal cooperators who
provide the data for this annual survey. For additional information, contact
Dr. Ronald Billings, Texas Forest Service, at (979) 458-6650 or by e-mail at rbillings@tfs.tamu.edu .