Ornamental Plants Annual Reports and Research Reviews 2004

Special Circular 195

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Gypsy Moth in Ohio

David Adkins, Amy K. Stone, and Daniel A. Herms

Introduction

The gypsy moth, Lymantria dispar (L.), is one of the most notorious and destructive insect pests threatening our hardwood forests and ornamental landscape plants in Ohio. The caterpillar stage of the insect feeds on more than 300 species of trees and shrubs. Favorites include oaks, aspens, birches, lindens, sweetgum, crabapples, hawthorns, mountain ash, and willows. Severe defoliation can weaken trees, leaving them more susceptible to other stresses, such as drought, disease, and other insect pests including borers.

Since its accidental introduction in Massachusetts in 1869, this non-native insect has steadily moved throughout the New England and North Atlantic states down to northern North Carolina and west to the states surrounding the Great Lakes Region, including Ohio. Infestations have also occurred in the west coast states of Washington, Oregon, California, and Utah.

The first adult male moths in Ohio were trapped in 1971, in Ashtabula County. Two years later, the first chemical eradication program was implemented by the Ohio Department of Agriculture (ODA). For the next 15 years (1973 through 1987), efforts were aimed exclusively at the eradication of localized gypsy moth populations. Despite this effort, the population continued to grow. In 1987, Ashtabula County became the first Ohio county to have gypsy moth quarantine regulations imposed. Additional townships in three contiguous counties (Trumbull, Lake, and Geauga) were also regulated at the same time. Since then, 42 more counties have been added to the quarantine list in Ohio.

In 1989, ODA, in conjunction with the U.S. Department of Agriculture (USDA) Forest Service, initiated the Gypsy Moth Suppression Program with a two-acre treatment block in Geneva State Park, in Ashtabula County. The Gypsy Moth Suppression Program continues today, but is now a voluntary treatment at the request of the landowner/landowners meeting the program’s minimum qualifications.

Figure 1. The map indicates three zones in Ohio

In 1998, pheromone traps were placed over the entire state of Ohio, in eight-kilometer grids. This was done to estimate the infestation densities of the gypsy moth across the Buckeye State. With this data, an infestation line was drawn (the 10-moth line), with the area to the east of this line being considered generally infested. The suppression program generally operates in this area.

In 1999, the Slow the Spread (STS) Program was added by USDA’s Forest Service and Animal Plant Health Inspection Service (APHIS) in Ohio as a means of monitoring the advancement and to eradicate populations of gypsy moth that were ahead of the infestation line. A 100-kilometer swath paralleling the infestation line to the west was established and this became the STS Action Zone. This STS zone passes through eight states.

The activities and results that ODA was able to accomplish in 2004 related to the gypsy moth in Ohio are described here.

The Suppression Program

In the fall of 2003, ODA received nine suppression survey applications for consideration for the 2004 program. Applications came from Coshocton, Holmes, Jefferson, Licking, Lucas, Morgan, and Sandusky Counties. After review of the applications and a survey of the blocks, it was determined that only one application qualified for suppression treatment.

Minimum qualifications that must be met to be included in ODA Suppression Program include the following:

1. A fully completed application must be received by ODA no later than September 1 of the year prior to treatment.
2. The proposed spray block must be located in a county that has been designated in the quarantine for gypsy moth by ODA.
3. The proposed spray block must contain a minimum of 50 contiguous acres.
4. The proposed spray block must have a concentration of at least 250 egg masses per acre in forested residential areas and 1,000 egg masses per acre in uninhabited forested areas.
5. The proposed spray block must have a tree canopy that covers no less than 50% of the block.
6. The proposed spray block must consist of at least 35% tree species that are either susceptible or resistant to gypsy moth.
7. The proposed spray block must receive a favorable T&E Assessment from the Ohio Department Natural Resources (ODNR) and the U.S. Fish and Wildlife Service.
8. ODA must receive the total cost share payment from the landowner no later than March 1 of the treatment year.*

Figure 2. Location of the 2004 Treatment Block in Lucas County.

* In the fall of 2004, ODA implemented a Landowner Cost Share as part of the Suppression Program. Landowners whose applications qualify for a suppression treatment will be required to pay 50% of the average cost of application of the project before their land is treated. Under the current aerial contract, the cost to the landowner would range from $8.90 to $22.49 per acre, depending on total acres treated and products used.

In 2004, the single suppression treatment block was located in Lucas County, east of Swanton, Ohio. The 294-acre Swanton block was located in the Whitehouse quadrangle and was made up of forested residential and private recreational land use.

The pre-treatment egg mass count was 6,914 egg masses per acre (EM/A). Two applications of Foray 48F, a microbial insecticide Bacillus thuringienis var. kurstaki (Btk), was applied at the rate of 24 BIU/A/application. Amy Stone, Extension Educator with Ohio State University Extension in Lucas County, acted as block coordinator.

The first application was made on May 12 at 9 a.m. Weather conditions at the time were:
     temperature: 75° F
     relative humidity: 71%
     wind speed : 1 to 3 mph.

The second application followed five days later on May 17 at 7:51 a.m. The weather conditions at the time were:
     temperature: 62° F
     relative humidity: 80%
     wind speed : 3 to 5 mph.

The weather readings were made at ground level within the treatment block.

A post-treatment egg mass count conducted by ODA in October found 165 EM/A. This was a 97.6% reduction in the population.

Slow the Spread Program

1. The Eradication Treatment Project

Five treatment blocks were targeted for eradication treatments in 2004 for a total of 2,548 acres (Table 1). All blocks received two applications of Foray 48F, a microbial insecticide Bacillus thuringienis var. kurstaki (Btk), at the rate of 24 BIU/A/application.

Figure 3. STS Eradication Treatment Locations, 2004.

STS Eradication Treatment Locations

The first round of treatments began at Pike State Forest on May 5, with the second round concluding on May 17, 2004. Because of the wide range of leaf and larva development between the Pike SF Block and the Oakwood Block, both treatment applications to the Pike SF, Catawba, and Mingo Blocks were completed before moving to the Mt. Victory and Oakwood Blocks for their first application.

The results of ODA treatments, based on the findings of the trapping in and surrounding the treatment blocks (delimit trapping), indicated a 100% control in four of the five blocks. In the Oakwood Block, male moths were caught again, but at a greatly reduced number. Because of the catches in the Oakwood Block, it will be treated again in 2005.

2. Mating Disruption Treatment Project

Fifteen blocks were targeted in 2004 for mating disruption treatments, for a total of 82,761 acres (Table 4). Applications of Disrupt II flakes, a gypsy moth mating disruptant, were made at either the 6 gram or 15 gram rate (Table 5), depending on the moth catch levels obtained during trapping in 2003. Trapping will be conducted again in 2005 to determine the effectiveness of the treatment. The Vinton Block was used as a test plot for a new mating disruption product from 3M.

Figure 4. Mating Disruption Treatment Locations, 2004.

In 2004, mating disruption treatment blocks from 2003 were trapped to determine the effectiveness of the treatment. Six of the 11 treatment blocks — New Moorefield, Cedarville, Bellbrook, Trenton, Hanging Rock, and East Cincinnati — showed an excellent result, with 100% reduction in moth catches. The South Webster block had a good treatment result with a 92.9% reduction in moth catches. The last four blocks had less than expected results.

The Morgantown and Bainbridge Blocks are scheduled to be treated again in 2005 as parts of the larger Anerville 05 and Lapperall 05 treatment blocks, respectfully. This time around, a Btk treatment is planned. The Bourneville and Summit Hill Blocks are listed as areas of concern in the STS Decision. This northern Pike County and southern Ross County area continues to be a problem site. Stronger efforts are planned in 2005.

3. Trapping Survey Project

Pheromone traps were placed in all or part of 66 of Ohio’s 88 counties in 2004 to monitor the advancement of the gypsy moth population and isolated hot spots within the STS Monitoring and Action Zone, as well as the APHIS monitoring Zone. This amounted to trapping in 28,413 square miles of Ohio. Delta traps were used in monitoring and action areas, and milk-carton traps were used in delimit areas.

The state was divided into 38 trapping territories. Thirty-eight trappers and five crew leaders were hired on a seasonal basis, with one trapper assigned to each territory. Each crew leader was assigned to oversee seven or eight trappers. Each trapper, on average, was asked to set 359 traps.

Trappers started setting traps May 23. Delimit traps had to be set by June 19, with all others having a deadline of June 26. Midseason counts were to be completed between June 27 and July 31. Final counts and pulls could begin August 1, with an August 28 completion date.

A total of 13,645 trap placements were proposed in 2004, with 13,457 traps actually placed (98.7%). A total of 188 traps were omitted (1.38%) for one of the following reasons — inaccessible terrain, no structure to hang the trap on, access denied by landowner, or safety hazard. Of the traps that were placed, 1,074 traps (8.0%) were placed outside their target circle. Midseason checks were done on 10,618 traps (78.9%) and final trap pulls and counts were done on 13,403 traps (99.6%).

Figure 5. Smoothed Moth Counts, 2004.

Positive trap catches were reported on 2,090 traps (15.6%), with a total of 21,603 male moths caught. The highest single trap catch was 1,005, in the Springfield quadrangle. The county with the highest total catch was Licking County at 2,267 moths. Lucas County had the highest per trap average at 54.54 moths.

Over all, the 10-moth line in Ohio has receded again this year. Since 2001, the 10-moth line has receded just a little more each year. Even though the general movement west has slowed, more concentrated hot spots are showing up in the STS Action Zone.

The average catch per trap went up in 18 counties, stayed the same in four counties, and decreased in 44 counties in 2004, compared to 2003 averages. Of the 18 counties that showed increases, 10 were within the STS Action Zone, and three were within the APHIS Monitoring Area, and five were in counties in the Suppression Area.

APHIS Program

Since the southwestern corner of Ohio is outside the 100-kilometer STS Action Zone, ODA runs a trapping survey project for USDA-APHIS in this area. The area includes all or parts of Brown, Butler, Clermont, Darke, Hamilton, Mercer, Miami, Montgomery, Preble, Shelby, and Warren Counties.

Approximately 3,428 square miles were trapped on 2 and 3 kilometer grids. Eleven 500-meter delimits were placed within the larger grids. A total of 1,625 traps were set. Fifty positive traps were reported, with a total catch of 80 male moths, a 0.05 average catch per trap.

One mating disruption treatment block fell within the APHIS area in 2004. The Middletown Block, which was basically the Miami University campus, was treated with 6 grams per acre of Disrupt II. STS paid for the treatment.

Defoliation Survey

In cooperation with ODNR and ODA, an aerial defoliation survey was conducted over the entire state, starting the last week of June and concluding mid-July. Five-minute and three-minute flight lines were flown, depending on visibility, in an east-west direction. The survey was delayed a couple weeks due to the lack of availability of a plane and pilot from ODOT. This made detection more difficult because peak defoliation had passed, and the trees were starting to shoot new leaves.

After identifying potential defoliation and mortality sites from the air, ground surveys were conducted to verify the cause of the defoliation or mortality. Seventy-one sites in nineteen counties showed signs of gypsy moth defoliation or mortality. A total of 5,305 acres of defoliation and 555 acres of mortality were confirmed. This is a 21.7% increase in defoliation and a 15.2 % increase in mortality from 2003.

Figure 6. Defoliation and Mortality Locations, 2004.

Quarantine Counties

A county may be designated as generally infested with gypsy moth and quarantine regulations may be set if any one of the following are met:

Figure 7. Gypsy Moth Quarantined Counties, 2004.

1. When the majority (51%) of a county is behind the 10-moth per trap boundary line for three consecutive years (as the 10-moth line is plotted by the Slow-the-Spread strategy).
2. When 10 or more male gypsy moths are caught per trap in more than one-third of the detection traps, and alternate gypsy moth life stages are documented at multiple locations throughout the county.
3. When, after three consecutive years of program-recommended control efforts during which there are two consecutive years of delimiting surveys, an expanding gypsy moth population persists and multiple life stages are documented.
4. In the absence of meeting any of the previous criteria, when the federal and state regulatory officials determine that a potential for gypsy moth spread exists, they may mutually request that the county be regulated.

The criteria for designating a previously regulated county for gypsy moth as deregulated (free from gypsy moth) is:

1. Three consecutive years of negative trap data, with two consecutive seasons of delimiting trapping.

Regulated articles under the quarantine include trees and woody shrubs (including cut Christmas trees); logs; pulpwood; slabwood; firewood; wood-bark chips; outdoor household articles (tables, benches, chairs, doghouses, birdhouses, feeders, planters, utility sheds, grills, garden equipment, playhouses, sandboxes, recreational vehicles, boats, trailers, tents); and any other product or article that may carry a life stage of the gypsy moth.

After reviewing the trap catches, ODA did not add any additional counties to the Gypsy Moth Quarantine list. Currently, 43 counties in Ohio are under the quarantine regulations. The counties are Ashland, Ashtabula, Belmont, Carroll, Columbiana, Coshocton, Cuyahoga, Defiance, Erie, Fairfield, Fulton, Geauga, Guernsey, Harrison, Henry, Hocking, Holmes, Huron, Jefferson, Knox, Lake, Licking, Lorain, Lucas, Mahoning, Medina, Monroe, Morgan, Muskingum, Noble, Ottawa, Perry, Portage, Richland, Sandusky, Stark, Summit, Trumbull, Tuscarawas, Washington, Wayne, Williams, and Wood Counties.

David Adkins, Ohio Department of Agriculture, Gypsy Moth Program Manager; Amy K. Stone, Ohio State University Extension, Lucas County; Daniel A. Herms, Associate Professor, Ohio State University, Ohio Agricultural Research and Development Center (OARDC).