AAAI Products

4. Project Name: Optimization Trials, Operational Evaluations and Adult Efficacy Trials of Reduced Agent-Area Treatments for Control of Rangeland Grasshoppers Country: United States of America
Project Location within Country: Wyoming Professional Staff Provided by your Company
Research Leader, Research Associate and field staff 
No of Staff:
No of Man-months: 8
Name of Client: Uniroyal Chemical Company Approx. Value of Services: US $ 75,000
Start Date (month/year): May 1999 Completion Date: (month/year): December 2000
Name of associated firm(s) if any:
-Wyoming Department of Agriculture 
-Platte County Weed & Pest District 
-Goshen County Weed & Pest District 
-United States Department of Agriculture (USDA)
No. of Man-months of professional staff provided by associated firm(s):
Name of Senior Staff (Director/Co-ordinator, Team Leader) involved and functions performed: 

Jeffrey Lockwood (University of Wyoming, AAAI), Project Director: Responsible for design, development, analysis, and oversight of the trials. 
Scott Schell (University of Wyoming), Field Coordinator: Responsible for implementation of the trials, including communications with land owners, agencies, and applicators, and logistical management of the trial sites.

Detailed Narrative Description of Project:

Overview: Reduced Agent-Area Treatments (RAATs) were developed in Wyoming and this approach is being adopted throughout the western United States and other countries. RAATs is a method of integrated pest management (IPM) for rangeland grasshoppers, in which the rate of insecticide is reduced from traditional levels and untreated swaths (refuges) are alternated with treated swaths.RAATs works viaChemical Control (grasshoppers are killed in treated swaths and as they move out of untreated swaths) andConservation Biological Control (predators and parasites preserved in untreated swaths suppress grasshoppers).This approach can reduce the cost of control and the amount of insecticide by >50%. 

1999 Summary: The research was designed to addressed four objectives: 1) determine if Dimilin 2 UL (diflubenzuron) could be effectively integrated into a RAATs program, using a range of rates (0.75 to 1.0 oz/ac) and coverages (33, 50, and 100%) applied to replicated, small-scale (40-ac) trials, 2) determine if Dimilin could be successfully used under adverse environmental conditions (ground temperature exceeding air temperature by 15oF), 3) assess the performance of Dimilin in large-scale, operational conditions using low total volumes (8 to 12 oz/ac versus 30 oz/ac) of application, and 4) initiate a field evaluation of the effects of Dimilin (blanket application) on an adult-dominated infestation. 

The application of Dimilin at 0.75 or 1 oz/ac in a blanket application resulted in >95% mortality at 14-21 d after treatment. Under optimal (cool) conditions, the RAATs applications (expressed as oz of Dimilin per acre - percent coverage:1-50, 1-33, 0.75-50, and 0.75-33) yielded 94-99% mortality at 14-21 d after treatment. Control levels resulting from applications during sub-optimal (hot) conditions with the higher coverage (50%) and/or rates (1 oz/ac) RAATs applications were largely indistinguishable (<5% difference in mortality) from those obtained under cool conditions, but mortality was reduced in the low coverage-rate (0.75-33) treatments under hot conditions.As such, it appears that the 0.75-50 RAATs strategy provides at excellent mortality (>90% under all conditions) with just 38% of the Dimilin that would have been used in a traditional (1-100) treatment.This approach represented the lowest total amount of Dimilin necessary to yield mortalities under both cool and hot conditions that were statistically indistiguishable from blanket applications.Under operational conditions at low volumes, Dimilin (1-50) provided >95% mortality, suggesting the viability of using 8-12 oz total volume in RAATs applications.The treatment of a grasshopper infestation comprised primarily of adults yielded 33% mortality (corresponding to the proportion of late instar nymphs in the populations), and the population dynamics will be monitored in 2000 to determine the effect of Dimilin on the reproduction of the treated adults. 

2000 Summary: The research was designed to addressed five objectives: 1) refine the use of Dimilin 2L (diflubenzuron) in a RAATs program via testing of: two volumes (12 and 24 fl oz; 355 and 710 ml), two rates (0.75 to 1.0 fl. oz/ac; 55 to 73 ml/ha), and two coverages (33 and 50% with 100 ft [30 m] swaths) applied to replicated, small-scale (40-ac; 16 ha) plots;2) determine if these Dimilin-RAATs treatments could be successfully used under adverse environmental conditions (ground temperature exceeding air temperature by 15oF; 10oC); 3) determine if the substitution of canola oil (a known attractant and potential feeding stimulant of grasshoppers) for crop oil in the carrier formula allows the successful use of ultra-low coverage RAATs (25 and 33%); 4) assess the performance of Dimilin-RAATs (33% coverage) in a large-scale (920 ac; 372 ha) trial under operational conditions using canola oil as the carrier;5) conclude a field evaluation of the effects of Dimilin (blanket application) on an adult-dominated infestation treated in 1999. 

All Dimilin-RAAT methods [expressed as fluid oz of Dimilin per acre - percent coverage - volume of carrier in fluid oz (ml of Dimilin per ha - percent coverage - volume of carrier in ml)] ranging from 1-50-24 (30-50-710) to 0.75-33-12 (22-33-355) applied under optimal thermal conditions resulted in >98% mortality at 21 d after treatment. Thus, applying 0.75 oz (22 ml) of Dimilin in 12 oz (355 ml) of total volume to one-third of the infestation was as effective as applying 1 oz (30 ml) of Dimilin in 24 oz (710 ml) of total volume to one-half of the infestation after 21 d.The higher rates, volumes, and coverages may lead to greater mortality at 14 d, but these marginal advantages are lost by 21 d. 

In a striking consistency between the 1999 and 2000 data, application of 0.75 oz (22 ml) of Dimilin with 50% coverage provided >85% mortality at 14 d under all conditions on every treated plot. As such, it appears that the 0.75-50-12 (22-50-355) RAATs strategy provides excellent mortality with just 38% of the Dimilin that would have been used in a traditional 1-100-30 (30-100-887) treatment. However, the 33% coverage treatments appear to be equally viable under the environmental and operational conditions of our trials, and these applications use only 25% of the product that would have been applied in a standard, blanket treatment. 

Under adverse (hot) conditions, the Dimilin-RAATs treatments were somewhat less effective.At 14 d, the mortality in these plots was generally 5 to 10% lower than the plots treated under optimal (cool) conditions.By 21 d, all of the treatments conducted under hot conditions yielded >90% control and were statistically indistinguishable from the other plots. 

The use of canola oil as a carrier of Dimilin in a RAATs program did not enhance control relative to crop oil under most conditions (comparisons of 33% coverage).Under adverse hot conditions, canola oil appeared to result in more rapid mortality. However, under optimal (cool) conditions, Dimilin applied in crop oil was somewhat more efficacious than canola oil based treatments.Under both optimal and adverse conditions, the 1-25-24 (30-25-710) application of Dimilin with canola oil yielded >95% control by 21 d after treatment of 80 ac (32 ha) plots. 

The large scale (920 acre; 372 ha) operational test of the Dimilin-RAATs (1-33-24 or 30-33-710) was completely successful.At 7 d, grasshopper densities were reduced by 64% -- from 41.6 to 18.4 grasshoppers/m2. By 14 d mortality was 93%, and at 21 d the mortality reached 96%. 

The grasshopper nymph population densities in the area that was treated when the grasshoppers were primarily adults in July of 1999 were assessed weekly from 15 May to 28 June, 2000.For 4 of the first 5 wk, the nymphal densities were significantly lower in the treated plots. On 14 June, the population density in the untreated plots was 8-times higher than in the treated plots (20.6 vs. 2.6 grasshoppers/m2).In the 6th week, the population increased markedly in the northern, treated plot due to invasion from adjacent rangelands. Grasshopper densities never rose above 2.0 grasshoppers/m2 in the southern, treated plot. The populations in the two untreated plots increased through the first 4 wk of monitoring, then rapidly decreased as a mobile pest species, Aulocara elliotti, reached maturity and emigrated from the drought stricken habitat.

Detailed Description of Actual Services provided by your Company:see previous section
Firmís Name: Association for Applied Acridology International (AAAI)

AAAI Products
AAAI Contents