United States 

Department of 

Agriculture

Forest 

Service 

Intermountain 

Region 

Forest Health Protection 

Boise Field Office 

1249 South Vinnell Way, Suite 200 

Boise, ID 83709-1663

 Caring for the Land and Serving People Printed on Recycled Paper 

File Code: 3420 Date: April 21, 2005 

Route To: 

Subject: Forest Health Protection Report BFO-PR-05-03 

To: Forest Supervisor, Boise NF 

 

 

Enclosed is Forest Health Protection project report, BFO-PR-05-03. In this report, Carl 

Jorgensen, Boise Field Office Entomologist, evaluated the biological control agent, Mecinus 

janthinus, for population establishment and impacts to Dalmatian toadflax near Atlanta, ID. The 

objective of the monitoring was to determine the establishment of M. janthinus from previous 

releases, and document its impacts to the Dalmatian toadflax population. Charlie Swearingen, 

Idaho City Ranger District Range Technician, initiated the releases of M. janthinus and other 

biological agents for Dalmatian toadflax near Atlanta, but he was not able to determine 

biological control agent establishment or impacts on the weed. 

If you have any questions, please contact Carl Jorgensen at 373-4225 or Dayle Bennett at 

373-4227 in the Forest Health Protection Boise Field Office. 

For FHP evaluations, project reports, and trip reports on this or other topics visit our Web site at: 

http://fsweb.r4.fs.fed.us/unit/spf/tripreports/bk_beetle.shtml. For more general information on 

FHP programs and services visit our combined Regions 1 and 4 Web site at: 

http://www.fs.fed.us/r1-r4/spf/fhp/ or visit our national FHP Web site at: 

http://www.fs.fed.us/foresthealth/. 

/s/ Dayle D. Bennett (for) 

WILLIAM W. BOETTCHER 

Director, State and Private Forestry 

 

Enclosure 

cc: Warren Ririe, Joy C Roberts, Carl L Jorgensen, Dwight Scarbrough, Dayle D Bennett, 

Charles T Swearingen 

CJorgensen:al 
(Blank Page) 
Monitoring Mecinus janthinus for Population Establishment 

and Impacts to Dalmatian Toadflax near Atlanta, ID 

Report: BFO-PR-05-03 

Prepared by: 

Carl Jorgensen 

Entomologist 

Boise Field Office 

April 15, 2005 

Forest Health Protection 

Intermountain Region 

1249 South Vinnell Way, Suite 200 

Boise, ID 83709 
Introduction 

The Dalmatian toadflax infestation around Atlanta, ID was approaching 3,000 acres in 

2004. Conventional efforts and previous biological control releases have failed to 

manage the weed, so stem-boring weevils, Mecinus janthinus, were released in 2000. 

Additional releases were made in 2001, 2002, and 2003. Other agents released in the 

Atlanta area include: toadflax flower-feeding beetle, Brachypterous pulicarius; toadflax 

seed weed capsule weevil, Gymnetron antirrhini; and toadflax moth, Calophasia lunula. 

Brachypterous pulicarius historically has reduced seed production on yellow toadflax, 

but B. pulicarius impacts on Dalmatian toadflax are still unclear. Gymnetron antirrhini is 

widely distributed on yellow toadflax, but it is unknown if 1998 releases of G. antirrhini in 

Montana and Wyoming established on Dalmatian toadflax, as well as the 2001 release 

sites near Atlanta. These other insects have established on yellow toadflax, but have 

not been shown to establish and impact Dalmatian toadflax populations in the West. 

Mecinus janthinus has reduced Dalmatian toadflax densities at a number of sites in 

British Columbia and is well established and has shown to impact Dalmatian toadflax 

densities in northern Idaho and eastern Washington. The objectives of the monitoring 

were to determine if M. janthinus has established and if there are impacts to the 

Dalmatian toadflax at the release sites near Atlanta. Monitoring was concentrated on 

the M. janthinus release sites for two reasons. The first reason is the other biological 

control agents are more adapted to yellow toadflax and likely did not establish near 

Atlanta. The second reason was these M. janthinus release sites have not had similar 

population increases and impacts on weed populations compared to sites in northern 

Idaho. 

Methods 

Eleven M. janthinus release sites were monitored near Atlanta during July 1-2, 2004. 

Release sites were located using a GeoExplorer 3 GPS unit and maps of the release 

sites. Charlie Swearingen, Forestry Range Technician, Idaho City Ranger District, 

assisted the crew in finding and monitoring the sites. 

At each of the surveyed release sites, monitoring crews first conducted a 15-minute 

visual search for biological control agents and pinhole feeding damage by the adult 

weevils within 30 meters of the release site stake that monumented the release site. 

The weed stem counts per meter and weed height (cm) were recorded in the cardinal 

directions at 5, 10, and 15 meters from the release site stake. Percent cover for the 

target weed, tree, shrub, forbs, grass, litter, bare ground, and rock was estimated and 

recorded for the area within 30 meters of the release site stake. The stems per meter, 

weed height, and percent cover data were recorded to provide baseline data for 

comparison of future readings of the site. 
The M. janthinus populations at the release sites were evaluated and recorded into one 

of the following categories: 

 1. "None" was recorded when no agents and no damage from the weevils on 

Dalmatian toadflax were found. 

 2. "Present" was recorded when less than five M. janthinus were found, or pinholefeeding damage from the adult weevils was found in absence of weevils. 

 3. "Established" was recorded when more than one to five weevils per minute were 

found, or there was pinhole-feeding damage on most of the Dalmatian toadflax plants. 

 4. "Marginally collectable" was recorded when 6-15 weevils per minute were 

found indicating a healthy population of breeding adults and there was pinhole-feeding 

damage on most of the Dalmatian toadflax plants. 

 5. "Collectable" was recorded when weevil counts of greater than 20 per minute 

were found indicating the weevil population is in outbreak status and the population 

ready for redistribution. 

Results 

A total of 11 sites were monitored for M. janthinus and Dalmatian toadflax population 

levels. The insects or damage caused by the insects were found at all but two of the 

sites. At sites Unburn 3 and Unburn 4, no agents or evidence of the agents were found 

(Figure 1). The M. janthinus populations at eight surveyed sites were classified as 

"present". Fewer than five adult weevils were found and there was some pinhole 

feeding damage by the adult weevils found on the Dalmatian toadflax. The Riverbottom 

site was the only site classified as "established." There was excessive feeding damage 

and five adults were found at this site. Because of the amount of feeding damage to the 

Dalmatian toadflax and the number of adults found, the Riverbottom site probably has 

the highest population of M. janthinus in the Atlanta area. 

Discussion and Recommendations 

Although it appears M. janthinus has become or will become established in the Atlanta 

area, it has not had the same impacts to the Dalmatian toadflax populations as reported 

by land managers in the northern Idaho. These sites should be monitored in the future 

to continue evaluating and documenting the establishment of M. janthinus and 

associated impacts on the Dalmatian toadflax. 
There are several improvements that can be made to the sampling protocol and 

classification of M. janthinus populations. The first improvement is to drop the "present" 

population classification, and use "established" as the classification, to indicate 

presence and establishment of the weevils. If there were biological control agents near 

the release site after 2 or 3 years from release, the biological agents were present and 

have established a breeding population that can persist on the site. 

The second improvement is to change the sampling protocol for these weevils. During 

the visual surveys, the insects can fall from the plant before the observer sees them. A 

sampling technique that should be implemented is to use a bucket during the visual 

survey and gently shake or tap the plants over the bucket. Mecinus janthinus reacts to 

such motion by playing dead and falling from the plant. The bucket can be utilized to 

collect the falling weevils to get a more accurate count of the number of adults feeding 

in an area. Another change to the sampling protocol is to evaluate the last year stems 

for larval and pupal activity. The toadflax stems from last year can be split open to 

show the M. janthinus pupal chambers, larval galleries, and egg laying sites by the 

female weevils. 

In late June 2005, Charlie Swearingen and I will meet with Mark Schwarzlaender, 

University of Idaho Biological Control Specialist, to compare Mark's release sites in 

northern Idaho with the releases that Charlie has made on the Boise National Forest 

near Atlanta. Mark has had success in establishing M. janthinus sites in northern Idaho 

and is also puzzled by the lack of population buildup in the Atlanta area. Through our 

collaboration, we hope to determine why the M. janthinus populations at the Atlanta 

sites are not increasing like those in northern Idaho. 

It is a positive sign that the weevils have established at most of the Atlanta release sites 

and we expect they will likely begin to impact the Dalmatian toadflax population. Some 

releases of biological control agents take longer to develop due to environmental or 

other conditions. At the Atlanta sites, M. janthinus populations may or may not increase 

to levels that cause significant damage to Dalmatian toadflax. Theses release sites 

should be monitored the next few years to determine if the weevil population increases 

and what affect it has on the target host. 
WILD 1

UNBURN 3

UNBURN 4

UNBURN 5

UNBURN 6

UNBURN 2

UNBURN 1

PIPE SPR

TRAIL HEAD 2

RIVER BOTTOM

RIVER TERRACE

POPULATION LEVELS

COLLECTABLEMARG COLLECTABLEESTABLISHEDPRESENT

1:20,000

NONE {

Figure 1. Estimated Mecinus janthinus population levels on Dalmatian toadflax at release sites near A
Appendix 1. Summary table for monitoring Mecinus janthinus on Dalmatian toadflax at release sites near Atlanta, ID, July 

 Air Temperature Percent of Weed Stage Weed Patch No. of Site Name Weather (Fahrenheit) Wind Seed Bolt Bud Flower Acres Population Level Agents RIVER TERRACE PARTLY CLOUDY 61-70 CALM 0 0 20 80 1-10 PRESENT 0 RIVER BOTTOM PARTLY CLOUDY 61-70 CALM 0 0 20 80 1-10 ESTABLISHED 5 TRAIL HEAD 2 PARTLY CLOUDY 61-70 MODERATE 0 20 20 60 1-10 PRESENT 4 PIPE SPRINGS CLOUDY 61-70 MODERATE 0 20 20 60 1-10 PRESENT 3 UNBURN 1 CLOUDY 71-80 LIGHT 10 20 20 50 1-10 PRESENT 1 UNBURN 2 CLOUDY 61-70 LIGHT 10 0 20 70 0.25-1 PRESENT 3 UNBURN3 CLOUDY 61-70 LIGHT 0 0 20 80 1-10 NONE 0 UNBURN 4 PARTLY CLOUDY 61-70 CALM 0 0 20 80 1-10 NONE 0 UNBURN 5 PARTLY CLOUDY 61-70 CALM 0 0 20 80 1-10 PRESENT 0 UNBURN 6 PARTLY CLOUDY 61-70 CALM 0 0 20 80 1-10 PRESENT 0 WILD 1 CLEAR 61-70 CALM 0 20 20 60 <.25 PRESENT 4 Appendix 1. Continued  Estimated Weed Canopy Percent Canopy Cover SITE_NAME Stems/meter Height (cm) Weed Tree Shrub Forb Grass Litter Bare Ground COMMENTS RIVER TERRACE 7.0 40 50 10 5 5 20 5 5 PIN HOLE FEEDINRIVER BOTTOM 5.0 40 40 20 10 10 10 5 5 LOTS OF FEEDINTRAIL HEAD 2 5.0 65 80 5 0 5 10 0 0 DAMAGE PRESENPIPE SPRINGS 5.0 60 80 5 0 0 15 0 0 DAMAGE PRESENUNBURN 1 10.0 60 70 5 0 5 10 5 5 UNBURN 2 10.0 60 60 5 5 10 10 5 5 UNBURN3 10.0 60 70 5 5 5 10 5 5 UNBURN 4 0.0 1 40 10 10 5 30 5 0 NO FEEDING UNBURN 5 10.0 40 70 5 5 5 10 5 0 PIN HOLE FEEDINUNBURN 6 10.0 50 70 5 5 5 10 5 0 PIN HOLE FEEDINWILD 1 5.0 54 40 10 20 10 15 0 5