Data Entry

Ms. Zimmerman has entered the information into the state databases as soon as the information was received. The information was then placed on National Agricultural Pest Information System, NAPIS. As of September 30, 1997, Ms. Zimmerman has entered 936 records into the state databases, see Table II.

Mail

The AT&T FTS-2000 Mail was accessed twice a week for messages and reports. Important pest information was forwarded to interested parties.

Biocontrol of Cereal Leaf Beetle

Two natural enemies were released for cereal leaf beetle in 1997 (Table III). Eighty-four releases were made in Big Horn, Hot Springs, Park, and Sheridan counties (Figure I). Tetrastichus julis was recovered in eighteen locations (Figure II).

Two new agents were released during 1997. They were Mecinus janthinus and Gymnetron linariae for Dalmatian Toadflax.

The Wyoming Weed & Pest Districts were responsible for 77 releases on noxious weeds during the 1997 fiscal year (Table V). A majority of the releases were made in Goshen county, as seen in Table VI. In 1997, a majority of the releases were made on private land (Table VII).

Delimiting surveys were conducted near positive finds from the previous year in Albany, Fremont, Teton, Washakie, and Yellowstone National Park (Figure IV). In 1996, fifteen gypsy moths were found (Figure V).

Gypsy Moth, 1997

Detection traps for gypsy moth (Lymantria dispar L.) have been placed in all of Wyoming’s counties as well as Yellowstone National Park. Delimiting surveys are being conducted near positive finds from the previous year in Laramie, Park, Sheridan, and Teton counties (Figure VI). The traps for 1997 have not been removed; therefore, it is unknown at this time how many gypsy moths were found. When the data becomes available, Ms. Zimmerman will place the information on NAPIS.

Biological Control Program – Data Management

Project Coordinator: Kiana Zimmerman

Maps and reports depicting pest and biocontrol agent distribution information were distributed to APHIS and the Biocontrol Steering Committee (See Appendix for 1997’s maps and PPQ Program Support section for a summary of activity). The 1997 information is incomplete at this time; updated maps will be produced with the information is complete.

CAPS Internet Information

Project Coordinator: Kiana Zimmerman

In 1996-1997, the Wyoming CAPS program’s World Wide Web page, http://w3.uwyo.edu/~caps/caps.html, has had 1,724 people visit it. It averaged five hits per day during the last year.

The site contains information on gypsy moth, karnal bunt, and cereal leaf beetle surveys, weed distribution maps, and maps of biocontrol activities on weeds and insects. The 1997 maps will be placed on the page when all of the information has been received and maps have been updated.

Several e-mail messages were received from people viewing the site. The messages were forwarded to interested parties.

Optimizing survey and treatment decision through mapping rangeland grasshopper population dynamics

Project Coordinator: Kiana Zimmerman and Jeff Lockwood

Next year’s grasshopper densities tend to be related to the previous year’s density. Markov chains allow predictions to be made based on the past. A location has two possible values not infested and infested, therefore there are four possibilities for grasshopper infestation transitions: not infested -> not infested, not infested -> infested, infested -> not infested, and infested -> infested. Using a two-state Markov chain, several questions can be answered. The first question is what proportion of the times did each transition occur. The one-step transition the probabilities of each transition can be determined

and represented in a matrix P.

P₀₀ is the probability that a location was not infested this year and will not be infested next year. P₀₁ is the probability that a location will be infested next year when it is not infested this year. The same applies for P₁₀ and P₁₁, but they are based on the location is infested this year. From P we can then ask what is the probability of each location being infested or not infested for x years. Using the recursive properties of two-state Markov chain the question of the number of years each location will be in each state can be answered.

P⁽ⁿ⁾ = P^(n-1) * P

The expected number of years each location will be in a state is:

With the following equation the question what is the expected number of years a locations will be in one state before switching to the other state can be answered.

with variances

For instance if a pixel was 1 (infested) for 15 out of 32 years it would have a 65% chance that if this year not infested that next year would not be infested and a 35% chance of being infested. However, if the pixel was infested this year there would be a 64% chance that the pixel would be infested next year and a 36% chance of not being infested. There is a 50% chance that if the pixel if not infested this year that it will remain constant, not infested, for five years. The pixel if it is not infested may be not infested in a five year period 50% of the time, 2.52 years, and the pixel is expected to remain not infested for 1.83 years before switching to infested.

The maps have not been completed, however as soon as they are finished they will be distributed.

Grasshopper Fact Sheets

Project Coordinator: Robert Pfadt

During FY 1997 four species fact sheets were composed and published September 1997. The species of grasshoppers treated were Boopedon nubilum, Melanoplus borealis, Melanoplus bruneri, and Melanoplus lakinus. Field observations, collections, caging, and photographing of four species were pursued in the summer of 1997 in preparation for composing and publishing a new set of fact sheets on the following species: Brachystola magna, Dissosteira longipennis, Melanoplus rugglesi, and Orphulella speciosa.

Evaluation of Reduced-input Management of Rangeland Grasshoppers

Project Coordinator: Jeff Lockwood

The use of Reduced Agent-Area Treatments (RAATs) for control of rangeland grasshoppers was tested on two large-scale plots under operational conditions. The first site was in southeastern Wyoming (Platte County), where grasshopper densities prior to treatment were 15/yd². We applied three insecticides: carbaryl (XLR formulation; standard blanket application of 16 oz/ac to 100% of a 40 ac plot; RAATs application of 8 oz/ac to 50% of a 640 ac plot), malathion (ULV formulation; standard blanket application of 8 oz/ac to 100% of a 40 ac plot; RAATs application of 4 oz/ac to 80% of a 640 ac plot), and fipronil (4 UL formulation; RAATs application of 14 oz/ac to 33% of a 640 ac plot). Average mortalities at 7-21 days after treatment, corrected for changes in population densities in an untreated plot, were 96% for blanket carbaryl, 86% for RAATs carbaryl, 91% for blanket malathion, 89% for RAATs malathion, and 99% for RAATs fipronil. Economic analyses revealed benefit:cost ratios of 0.88 for blanket carbaryl, 1.80 for RAATs carbaryl, 1.12 for blanket malathion, 1.54 for RAATs malathion, and 2.92 for RAATs fipronil.

The second site was in northern Wyoming (Campbell County), where grasshopper densities prior to treatment were 53/yd². We applied two insecticides: carbaryl (XLR formulation; standard blanket application of 16 oz/ac to 100% of a 40 ac plot; RAATs application of 8 oz/ac to 50% of a 640 ac plot) and fipronil (4 UL formulation; blanket application of 14 oz/ac to 100% of a 200 ac plot; RAATs application of 14 oz/ac to 33% of a 400 ac plot). Average mortalities at 7-21 days after treatment, corrected for changes in population densities in an untreated plot, were 91% for blanket carbaryl, 75% for RAATs carbaryl, 97% for blanket fipronil, and 87% for RAATs fipronil. Economic analyses revealed benefit:cost ratios of 0.83 for blanket carbaryl, 1.68 for RAATs carbaryl, 1.09 for blanket fipronil, and 2.31 for RAATs fipronil.

Thus, it appears that the RAATs approach to rangeland grasshopper management is a viable strategy in terms of economic returns under large-scale, operational conditions. This method allows markedly greater economic benefits, while decreasing the amount of insecticide used in control programs by 60-75%, compared with the traditional, blanket applications of insecticides. Future work should focus on the refinement of RAATs methods with these compounds, studies of the mechanisms through with this strategies achieves its results, and development of RAATs methods for other compounds (e.g., Dimilin).

Cereal leaf beetle – field insectary and re-distribution

Project Coordinator: Michael Brewer

Per project revisions based on state discussions with John Larsen, Wyoming PPQ, Niles Biological Control Laboratory, and small grain industry representatives in Park County, Wyoming, major thrusts of this project were 1) the release of Anaphes flavipes in the field insectary and grower cooperator fields (fields or parts of fields where the grower intended not to spray insecticide regardless of the cereal leaf beetle infestation) and 2) the recovery of Tetrastichus julis previously released in Wyoming during the last two years. Approximately 123,000 Anaphes flavipes were released in multiple fields of 25 grower cooperators in Park, Hot Springs, Sheridan, and Big Horn Counties, early May, 1997 through mid-July, 1997.

Tetrastichus julis was recovered from 19 sites in Park County during June, 1997. At these sites, 26 assessments were made by dissecting collected larvae (of all larval stages) to detect larval parasitoids. Of 717 larvae dissected, 24.8% were parasitized with Tetrastichus julis .

Rates of parasitism varied from 0-100% among the 26 assessments, dissecting approximately 30 larvae per assessment. High variability of parasitism is not unexpected given the recent introduction of this parasitoid. Tetrastichus julis appears well established. The extent to which it will provide cereal leaf beetle control is only partly shown by these data; assessment in additional years is needed to fully provide control assessment. Data specific to this project have been provided to CAPS.

Cereal leaf beetle – survey in Wyoming

Project Coordinator: Michael Brewer