Large-Scale Mosquito Control

A look at why Allstate Pest Control in SA uses Bayer’s Aqua K-Othrine Space Spray for large-scale mosquito control.

Space-spraying is the preferred method of application for large-scale mosquito control. It is particularly effective against mosquitoes when a mosquito-borne disease threat is imminent and rapid reduction in insect numbers is required. It can also be a method that is relied upon when resources are limited and other methods are either not practical or have not achieved adequate results.

Space-spraying is routinely carried out in many areas of the world as a crucial means to reduce the incidence of vector-borne diseases such as dengue fever, malaria, encephalitis and diseases caused by the Zika virus. It is also an important element in fly management programs.

I recently met with the CEO of Allstate Pest Control in SA, Vasili Tsoutouras – who is also the Chairman of AEPMA (Australian Environmental Pest Managers Association) – to learn more about his experience of space-spraying.

Allstate Pest Control has been performing large-scale mosquito control for about eight years. The company performs adulticiding when there an exotic species is detected or where outbreaks of vector disease are found, usually in areas where surveillance is performed by local, state and/or federal government authorities. Their product of choice for adulticiding is Aqua K-Othrine from Bayer.

“Aqua K-Othrine does the job of efficient knockdown, which is clearly very important,” explained Mr Tsoutouras, “but what makes Aqua K-Othrine a better product is its safety profile. It is diluted with water and the end product being sprayed is 99% water, which is very advantageous when compared to other non-aqueous products.”

In addition to being an EW (emulsion in water) formulation, Aqua K-Othrine also contains an anti-evaporant to protect the water-based spray droplets from evaporative water loss, which is referred to as FFAST (or Film Forming Aqueous Spray Technology).

As the spray droplets are formed, the anti-evaporant agent comes out of the solution and forms a protective skin around the droplets. This process – which is completed in less than a second – ensures that the droplets maintain their size and therefore impaction efficiency for much longer than water-diluted emulsifiable concentrates (or even standard EW formulations). They are comparable in efficacy to the oil-based and oil-diluted products, but with the added benefit of economy in use from using water as a diluent. There is also reduced environmental contamination compared to an oil-based spray.

Product visibility during application is important to ensure all areas have been treated. “We don’t find the visibility issue being a problem for our technicians performing the application,” said Mr Tsoutouras. “However, we have had clients concerned about whether the treatment was covering all required areas. To alleviate these concerns, we just add a carrier product to the solution to generate a fog that is visible.”

Fogging mosquitoes with Aqua K-Othrine can be carried out using cold foggers or hot (thermal) foggers. The most important reason for using these specialist types of spray equipment is to achieve the optimum droplet size for efficient contact with the pest (see Table 1). With the benefit of FFAST technology, Aqua K-Othrine can result in optimum droplet sizes being maintained for longer periods of time in all climatic conditions and is as effective as oil/diesel-diluted space-spray concentrates (see Table 2).

Table 1: Spray performance of various droplet sizes

Table 2. Comparison of qualities of space-spray products

With extremely low rates of use (the lowest application rate of any other space-spray in Australia), Aqua K-Othrine has a high level of safety. The active ingredient, deltamethrin, has a very good safety profile, which is reinforced by the range of use patterns which it is approved for globally (this includes recent registration for used against stored product pests). It is a space-spray with minimal flammability and smell and is low risk in terms of staining, potential damage to paintwork, toxicology and pollution.

Customers of Allstate Pest Control rely on Mr Tsoutouras to select the right product for the job. “Generally, we find that our relationship with clients means that they put their trust in our company to recommend products and techniques to be used in the management of mosquitoes,” said Mr Tsoutouras. “Customers understand that we are the professionals when it comes to application of specialty control products. Our experience in mosquito control clearly shows that Aqua K-Othrine is our best product option.”

Jim Westhead, Pest Territory Sales Manager, Bayer Environmental Science