Fighting Mosquitoes While Preserving Organic Standards
Keira J. Lucas, PhD
Deputy Executive Director
Organic farms are held to strict federal standards when it comes to the use of synthetic substances, including pesticides. According to the Code of Federal Regulations (7 CFR Part 205), if a prohibited substance is found at more than 5% of the allowed level for conventional crops, the affected agricultural products can no longer be sold, labeled, or marketed as organic.
Understandably, we sometimes hear concerns about how mosquito control, especially aerial treatments, might affect organic farming practices. At CMCD, we take these concerns seriously. To protect the integrity of certified organic farms in Collier County, we carefully track their locations and establish exclusion zones to prevent the application of synthetic control materials above these sensitive areas.
In addition, CMCD is proud to integrate products into our operations that align with organic standards. We use a variety of materials certified by the Organic Materials Review Institute (OMRI), meaning they are approved for use in and around organic farms.
One of these products is Merus 3.0, a plant-based mosquito control adulticide made from chrysanthemum flowers. It meets the USDA’s National Organic Program standards and is safe to use over crops. We’ve been using Merus 3.0 since 2018, especially during aerial treatments from our Bell 407 helicopter, to effectively control adult mosquitoes.
Many of the larvicides in our program are also OMRI-certified. These biorational microbial larvicides are made from naturally occurring soil bacteria. Products like AquaBac 200G, VectoBac WDG, and VectoMax FG are based on Bacillus thuringiensis israelensis (Bti) and also meet the USDA’s organic standards. These materials are highly targeted, affecting only mosquito larvae, midges and black flies, while remaining safe for people, pets, and the environment. In fact, if you’ve ever used mosquito dunks or mosquito bits around your home, you’ve already used Bti! It’s a trusted, natural solution that plays a key role in both household and large-scale mosquito control efforts.
We also apply larvicides from the Natular® product line, which contain Spinosad, a naturally derived active ingredient classified as a reduced risk larvicide. Like Bti, Spinosad is also sourced from a soil bacteria and meets the USDA’s organic standards. Spinosad adds another effective and environmentally responsible tool to our integrated mosquito management strategy.
The District’s field validation team is currently testing several natural mosquito control products that fall under a special EPA category called FIFRA Section 25(b) minimum risk pesticides. These products are generally considered safe in terms of exposure limits for humans and are often made from natural ingredients like essential oils or plant-based compounds. Because they are viewed as low risk, these products aren’t required to go through the same detailed testing and approval process as traditional pesticides. That also means there’s often less scientific data available to show how well they work, especially when it comes to non-target impacts and controlling mosquito populations and the diseases they may carry. The District is currently testing some of these products to see if they can be a reliable and effective option for mosquito control in our area.
While we are proud to include natural and OMRI-certified products in our program, it’s equally important to understand that our adulticide application methods themselves are designed to minimize environmental impact. Aerial ultra-low volume (ULV) applications using precise drift modeling are specifically intended to target adult mosquitoes in the air, not on the ground or crops. Our applications are distinctly different from agriculture sprays, where we work to treat the airspace with small amounts of aerosolized product. These aerosolized products have low settling velocities (Thistle, 2000), meaning they stay in the air longer rather than quickly falling to the ground. Studies have shown that these ULV applications result in very small amounts actually landing on the ground, water and crops (Dukes et al, 2004; Lothrop et al, 2007; Qui et al, 2021; Weston et al, 2006). In fact, many studies have shown that the amount that settles is much lower than those estimated by EPA’s risk assessments developed using agricultural spray algorithms (Schleier et al, 2007; Schleier et al, 2010).
When it comes to organic agriculture, a recent study has demonstrated that even frequent aerial ULV applications result in only small amounts of the additive piperonyl butoxide (PBO) on crop leaves, with both PBO and the insecticides pyrethrins and naled breaking down rapidly after each treatment (Qui et al, 2021). There was no buildup over time, and no detectable residues of these substances were found on the crop at harvest. These findings confirm that aerial ULV applications result in only trace levels of pesticide residues on organic crops and that these levels dissipate quickly and do not persist in the final food product.
By combining careful planning, certified organic-compatible materials, and targeted application methods, CMCD continues to effectively control mosquitoes while also supporting and safeguarding organic agriculture in our community.
For more information on organic certification, please visit USDA Agricultural Marketing Service.
For more information on organic farming in Collier County, please visit the USDA Organic Integrity Database.
Whether you’re a certified organic farm or a business exempt from certification, we’d love to hear from you! Let’s work together to find the best mosquito control options that won’t negatively impact your operations or your neighbors. Reach out to us at 239-436-1000 or info@cmcd.org.
References
Dukes J, Zhong H, Greer M, Hester P, Hogan D, Barber JAS. (2004) A comparison of two spray nozzle systems used to aerially apply the ultra-low volume adulticide fenthion. J Am Mosq Control Assoc. 20(1): 27-35.
Lothrop HD, Huang HZ, Lothrop BB, Gee S, Gomsi DE, Reisen WK. (2007) Deposition of pyrethrins and piperonyl butoxide following aerial ultra-low volume applications in the Coachella Valley, California. J Am Mosq Control Assoc. 23: 213-219.
Schleier JJ III, Peterson RKD, Macedo PA, Brown DA. (2007) Environmental concentrations, fate and risk assessment of pyrethrins and piperonyl butoxide after aerial ultra-low volume applications for adult mosquito management. Environ Tox and Chem. 27: 1063-1068.
Schleier JJ III, Peterson RKD. (2010) Deposition and air concentrations of permethrin and naled used for adult mosquito management. Archives Environ Contamination and Tox. 58: 105-111.
Thistle HW. (2000) The role of stability in fine pesticide droplet dispersion in the atmosphere: a review of physical concepts. Trans ASAE. 43:1409–13.
Qui J, Wheeler SS, Reed M, Goodman GW, Xiong Y, Sy ND, Ouyang G, Gan J. (2021) When vector control and organic farming intersect: Pesticide residues on rice plants from aerial mosquito sprays. Sci Total Environ. 773: 144708.
Weston DP, Amweg EL, Mekebri A, Ogle RS, Lydy MJ. (2006) Aquatic effects of aerial spraying for mosquito control over an urban area. Environ Sci Technol. 40:5817–5822.
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Dr. Keira Lucas serves as the Deputy Executive Director of the Collier Mosquito Control District, bringing a background in vector biology. She specializes in mosquito reproduction and biology, integrated pest management and pesticide resistance management, with experience in applying science-based strategies for effective and sustainable mosquito control.
