Micron - manufacturers of specialist spraying equipment

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Control of West Nile Virus in the US

Since the outbreak of West Nile Virus in New York City in 1999, Micronair aerial atomisers have been routinely used on fixed wing aircraft and helicopters to reduce mosquito populations and the threat of transmission of disease.  

Micronair aerial atomisers have, over the last 25 years, been widely used to treat adult mosquito populations for both disease and nuisance mosquito control in southern and eastern states of the US and across to California.  Mosquito larvacide applications to salt marshes have also been undertaken with Micronair aerial spray equipment, using Bti (Bacillus thuringensis israeliensis) and other products.  

Precise control of spray droplet size ensures that ultra low volumes of pesticide can be used optimally to minimise any adverse effects on the environment and non-target organisms.  Close operational control and monitoring ensure that applications are only made at the optimal time, often during the late evening or at night, and under stable wind and thermal conditions. Flying height should normally be about  30m above the ground to optimise spray dispersal.   Typically less than 100 ml/ha of spray liquid is applied with product dose rates often only 1 – 2 g ai/ha.  Recently a number of US State mosquito control organisations have re-equipped their aircraft with Micronair atomisers for control operations.  Recent research using a Malvern laser particle size analyser has demonstrated optimal spray droplet sizes produced by Micronair rotary atomisers with water based adulticide formulations.  Several US states have also recently equipped twin engine aircraft with self-contained Micronair Pod systems to treat urban areas.  Pods are equipped with flowmeter turbines, RPM indicators, variable restrictor units and check valves.  A control panel in the cockpit displays flow, total volume applied and area treated to assist in the monitoring and recording of spray operations.  

In the US States of Louisiana, Texas, New Jersey, New York and Florida, large scale mosquito control operations are under way to prevent the spread of West Nile Virus and to contain the disease.  Peak disease incidence coincides with the summer breeding of mosquito populations between June and August and aerial spraying is practiced during this period.  Combined with a sophisticated ground control operation (including routine surveys and targeting known mosquito breeding areas with 'soft' larvicides to break the breeding life cycle), this has provided an effective check to the spread of this serious disease.

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