Mosquito-borne diseases continue to pose a significant threat to public health worldwide, and with some mosquito populations developing resistance to long-used active ingredients, it is now more critical than ever to develop innovative solutions for mosquito control. As a company dedicated to advancing public health on a global scale, Clarke is developing, supplying, and providing effective and novel products to the needs of mosquito control districts and organizations – including those managing resistant mosquito populations.
This included working with the Salt Lake City Mosquito Abatement District (SLCMAD) to evaluate Clarke’s aerial adulticide product, Duet® HD, as a fit for their integrated mosquito management program. SLCMAD’s team recently detailed the results and overview of this trial in the Journal of the American Mosquito Control Association (JAMCA). Today, we will dive into the results shared by SLCMAD in JAMCA, including the field trials conducted by SLCMAD in Utah with members of Clarke’s field science team, and a highlight of Clarke’s Duet HD.
SLCMAD oversees a diverse coverage area with urban and suburban conclaves – as well as thousands of acres of wetlands, prime larval habitats for mosquitoes with limited road access. Given this, aerial applications are generally considered the most effective treatment method for these portions of SLCMAD.
Over the years, the district has also observed urban and suburban expansion closer to and into these previously undeveloped rural habitats. While historically the program relied on traditional organophosphates for their aerial adult control applications in these areas, the desire for more environmentally-friendly chemistries and the adoption of Integrated Mosquito Management (IMM) recommended practices for product rotation for resistance management led to a field trial study involving Duet HD, a pyrethroid-based insecticide.
Considering the city’s rapid expansion closer to and within wetland habitats, controlling mosquitoes before they depart the wetlands while aligning with IMM practices and public concerns became a priority. SLCMAD’s study design with Clarke focused on evaluating the effectiveness of Duet HD in their actual environment and operational conditions against wild populations of Aedes dorsalis and Culex tarsalis, in addition to insectary strains of SLCMAD’s colonies of Culex pipiens and Clarke’s colonies of Culex quinquefasciatus.
Duet HD, a subset of Clarke’s Duet adulticide line formulated specifically for aerial mosquito control, was selected for the trial by SLCMAD due to its carrier complex that increases its particle weight for greater foliage penetration, maximizes cloud density in the spray zone, and enhances cuticle penetration on targeted mosquitoes. It also contains an active ingredient novel to the one historically used by SLCMAD in aerial applications.
The field trial conformed to industry best practices – about which you can learn more here – with three aerial applications of Duet HD conducted on sampling stations containing Cx. pipiens, Cx. quinquefasciatus, Cx. tarsalis, and Ae. dorsalis. Knockdown and mortality were then assessed at timed intervals.
The Ae. dorsalis, Cx. pipiens, and Cx. quinquefasciatus colonies exhibited high susceptibility to Duet HD, though the Cx. tarsalis colony showed lower susceptibility. It should be noted that Cx. tarsalis demonstrated an average mortality rate trending above 75% at testing stations with higher levels of product droplets present. This reduced mortality was attributed to insecticide resistance within Cx. tarsalis populations to pyrethroids, as confirmed through bottle bioassay testing conducted by SLCMAD. The pyrethroid resistance is likely a result of agricultural, private pest, and home-owner usage of this class of pesticides
In terms of operational performance, the Duet HD applications produced robust spray clouds despite erratic wind conditions and an inability to offset the flight pattern due to the vicinity of the Salt Lake City International Airport. This spray cloud performance is attributed to Duet HD’s heavier formulation. When faced with these weather conditions, it may be beneficial to increase the product rate application to its maximum rate to offset these issues and achieve an even higher spray cloud density.
Ultimately, Duet HD demonstrated itself as an alternative to organophosphates for aerial applications by SLCMAD. The full design, implementation, and results of the study from SLCMAD can be accessed via JAMCA below.
Developed by Clarke, Duet HD is a mosquito control adulticide product formulated for aerial applications, with added weight, minimized vaporization for better cloud performance, and enhanced cuticle bonding and penetration. It utilizes a powerful combination of active ingredients, prallethrin and sumithrin, which have been proven to be highly reliable in controlling adult mosquito populations in Clarke’s original Duet formulation.
To gain more insight into the field trial results, we encourage you to read the full article from SLCMAD’s team for JAMCA. You can access the article directly on the Journal of the American Mosquito Control Association’s website:
SLCMAD’s Duet HD field trial sheds light on both the triumphs and challenges faced in operational mosquito control, where there is no one-size-fits-all product or solution for effective control of nuisance and disease populations. The study emphasizes the importance of testing mosquito control products in various operational conditions, habitats, and against a range of species to fully understand their fit and impact. It also underscores the continued need for alternative mosquito control strategies and products to ensure effective public health protection.
Thank you to the exceptional team at Salt Lake City Mosquito Abatement District for the opportunity to partner with you on this important work.
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