Spongy Moth Suppression and Eradication

The European spongy moth, Lymantria dispar (L.), is one of the most important forest pests in the United States. In Region 8, the leading edge of the generally infested area moved into northern Virginia in the early 1980’s. Since then, it has moved down the eastern part of the state, and from there moving south into northeastern North Carolina and southwest to about Interstate 77.

Suppression:

The first spongy moth cooperative suppression program in R8 was initiated on private land in northern Virginia in 1984 and treated 4,000 acres. The first national forest suppression project took place on the Lee Ranger District of the George Washington NF in 1986. Since that time, treatment acreage increased steadily reaching a peak in 1990 with approximately 230,000 acres being treated under the Appalachian Integrated Pest Management Program.

In 1992, the insect pathogen Entomophaga maimaiga, a fungus, was first confirmed in Prince William County; by 1995 it had spread throughout the generally infested region of Virginia. This fungus which thrives in moist spring weather, caused a general collapse of spongy moth populations throughout the generally infested area of the US from 1995 until 2000. As compared to the Northeastern Area (Region 9) where spongy moth was first introduced into the United States, the southeast has experienced minimal spongy moth defoliation. Dry spring weather from 2000 through 2003 caused a decrease in E. maimaiga resulting in an increase of spongy moth populations. Defoliation peaked in 2001 when 763,328 acres were reported as being defoliated. During the four year period from 2000 through 2003 a total of $2,559,518 was spent on suppression projects in Virginia.

Wet spring weather returned in 2003 and again the spongy moth populations collapsed from E. maimaiga; until 2006. From 2006 through 2009 spongy moth defoliated 228,245 acres. Wet spring weather this year caused a general collapse of spongy moth throughout the nation. 

Eradication:

In a Memorandum of Understanding with APHIS, the Forest Service is designated as the lead agency for conducting eradication projects on spongy moth infestations whose size is over 640 acres, or for those that occur on federal lands.

Since 1990 FHP has assisted in eradication projects in Georgia (’92, ’93, ’95, 96), Arkansas (’94, 95), North Carolina (’90-99, ’04-‘08), Virginia (’88-’89, ’99) and Tennessee (‘92, ‘94, ‘95, ‘97, ‘99, ’02-’05). Most of these infestations were associated with the movement of outdoor household items (eg. camper trailers).

In 2010 the Cherokee National Forest will be conducting an eradication program on 356 acres using mating disruption.

Detection:

In 1982, FHP implemented a spongy moth trapping program on federal lands to enhance state trapping programs. Each year in states serviced by the Asheville Field Office, 202 federal cooperators place 2,000 traps at 202 sites [DOD, DOE, BIA, NPS, F&WS, TVA, APHIS, and Army COE].

Program Highlights:

Cooperation: FHP provides technical assistance in all phases of spongy moth control. Control projects are run under an Incident Command System structure; FHP participation is an integral part of state and federal treatment programs.

In partnership with the Northeastern Area (Morgantown Field Office), state guidelines and standards have been developed for all state cooperators. Standardization has resulted in more effective treatment programs.

Training:

FHP personnel provide technical expertise in all phases of control programs, including: contracting, planning, field implementation of trapping, and the latest application technology.

Training is provided in the use of aerial application software developed by the Forest Service and in proper application techniques. (Advanced Pesticide Training; Annual State Cooperators Meetings; Spongy Moth Annual Review).

Technology:

In 1991, FHP began development of spongy moth management support software. The first product GypsES (Spongy Moth Expert System) was released in 1995 and was used by APHIS, US Air Force, state and county agencies, and private applicators. With assistance from Harold Thistle of the Forest Health Technology Enterprise Team, portions of the program were rewritten in 2001 to work within ArcView (“Spray Advisor”). Spray Advisor development now includes partners from the Canadian Forest Service and New Zealand Forest Research.

Specialty software has been developed to assist in project planning and treatment:

1. Calibrator– aircraft calibration software
2. THC– Temperature and humidity charting to determine proper environmental conditions for Btk application
3. CASPER– Program to estimate aircraft productivity and efficiency rates along with pilot flight hours.
4. BioSIM – software that predicts the timing of specific stages in an insect’s life cycle (egg, larva, adult) by using weather data (mainly temperature) at specific locations.

Conclusions:

State agencies are currently staffed with only a few well trained, experienced personnel. FHP technical assistance is often needed to assist in planning and executing large complex projects. This is a good opportunity for on-the-job training for other personnel.

Eradication treatment is often limited by state cost share, resulting in multi-year projects to cover large infestations. Increased cost share (75%) in line with STS would help, and in the long run reduce project costs.