APLC Insecticide and Application Technology Research

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APLC Insecticide and Application Technology Research

Barrier & Blanket treatments with fipronil to control Australian plague locust

Successful field testing of fipronil (Adonis 3UL) over the past three years has resulted in the APLC adopting this insecticide for control of nymphs in bands infesting rangeland pasture. Blanket or full cover treatments at a dose of 0.9g ai/ha (300 mL/ha) are applied using an aerial drift spraying technique with Micronair AU5000 atomisers (blade setting of 450), to blocks < 2km2 in size.

A 100 metre (m) spacing between spray runs is used with these treatments. Barrier treatments with a 500m spacing between spray runs, a 5 to 10m release height and a mean dose of 0.25g ai/ha are used with larger blocks. This form of treatment results in strips of dosed vegetation up to 300m wide downwind of each spray run, separated by areas with very low deposits of insecticide (< 10ug fipronil/ kg of vegetation). Due to the residual activity of this insecticide, marching bands of nymphs are likely to come into contact with dosed vegetation irrespective of their direction of movement. When daytime temperatures are >300C both methods of treatment kill >95 % of nymphs in target areas within 7 days of spraying. At lower temperatures it can take several more days to achieve the same result. Barrier treatments using fipronil offer rapid control of large areas with significant operational cost savings (reductions in spray aircraft flying time and quantity of insecticide used) and possible advantages to non-target species. Work is continuing to further refine the use of fipronil by the APLC.
 

spraying

Above: The ability to apply fipronil in widely placed strips (barrier treatment) will significantly reduce costs and the area sprayed with insecticide.

Use of DGPS during spraying operations

 All APLC contract spray aircraft now use Differential Global Positioning Satellite equipment to accurately mark target boundaries, determine correct spacings between spray runs and electronically record treated areas.

Use of DGPS has streamlined control operations by doing away with the need for ground marking of spray runs and allowing survey aircraft to better utilise flying time (no longer a need to monitor the progress of a spray aircraft once the boundaries of the target has been described to the pilot). DGPS records also provide precise information on the location of sprayed areas that can be used by the APLC when liaising with landholders and incorporated into APLC control data sets.

Wind tunnel studies with different pesticides

 The wind tunnel facility at the University of Queensland’s Centre for Spray Technology Application and Training (CPAS), was used to test ULV formulations of insecticides currently used or likely to be used by the APLC during control operations: fipronil (Tradename - Adonis 3UL), Green Guard (oil diluent with Metarhizium anisopliae spores) and diflubenzuron (Dimilin OF60). These insecticides were run through a Micronair AU5000 rotary atomiser with an airflow of 200km/hr to simulate aerial spraying. By varying flow rates and using a range of blade angles to vary rotational speed, data on the droplet spectra produced with each material were collected.

Together with similar data collected previously using fenitrothion (Sumithion ULV), this information allows study of theoretical deposition patterns to be carried out using models (such as AgDrift) to examine deposition patterns within sprayed areas, the extent of off-target drift under varying wind conditions and the effect that release height or wind speed has on deposition.

In addition, this data is useful for calibrating the AU5000 atomisers on spray aircraft used by the APLC. Actual cage RPM rather than blade angle is now used so that irrespective of the flying speed of the aircraft used (piston or turbine, range of 170 to 240km/hr), the spectrum of spray droplets generated during application will be within the same desired range. 

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Last reviewed: 06 Nov 2008
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