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Research Project: Integrated Management of Resistance and Population Expansion of Disease Vector and Nuisance Mosquitoes

Location: Mosquito and Fly Research

Title: Isoxazolines and a meta-diamide are effective mosquito larvicides against Aedes aegypti, Anopheles quadrimaculatus, and Culex quinquefasciatus

Author
item DAGG, KENDRA - University Of Florida
item SCOTT, JEFFREY - Cornell University
item VILLA, MILANI - University Of Florida
item MOSORE, MBA-TIHSSOMMAH - University Of Florida
item MERTZ, ROBERT - Cornell University
item Estep Iii, Alden
item BURGESS, EDWIN IV - University Of Florida

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2026
Publication Date: 4/9/2026
Citation: Dagg, K.A., Scott, J.G., Villa, M., Mosore, M., Mertz, R.W., Estep Iii, A.S., Burgess, E.R. 2026. Isoxazolines and a meta-diamide are effective mosquito larvicides against Aedes aegypti, Anopheles quadrimaculatus, and Culex quinquefasciatus. Journal of Medical Entomology. 63:2. https://doi.org/10.1093/jme/tjag053.
DOI: https://doi.org/10.1093/jme/tjag053

Interpretive Summary: Mosquito-borne diseases are an important challenge in global public health that necessitates control of mosquito vectors. Treatment of larvae is considered an important strategy for mosquito control, but a limited number of chemical classes that target larvae are available. Further, resistance to the chemical classes used to target adult mosquitoes can translate to resistance in both adults and larvae, further reducing the number of available chemicals for use against larvae. Thus, there is a need to explore new chemical control tools that will circumvent existing insecticide resistance via new modes of action, while also remaining safe to use near humans and animals. To address this need, University of Florida, Cornell University and USDA ARS CMAVE scientists examined several isoxazolines and meta-diamides for effectiveness in controlling three pest mosquitoes species. This evaluation included both insecticide susceptible and insecticide resistant strains to increase the field relevance of the findings. We found fluralaner was the most effective isoxazoline and that it had higher efficacy than spinosad, a commonly used mosquito larvicide. The results of this study indicate that the isoxazolines, which have a good safety profile in mammals, may be a useful chemistry for use in mosquito control, particularly in mosquitoes with resistance to common classes of pesticides.

Technical Abstract: Mosquito-borne diseases are an important challenge in global public health that necessitates control of mosquito vectors. Treatment of larvae is considered an important strategy for mosquito control, but a limited number of chemical classes that target larvae are available. Further, resistance to the chemical classes used to target adult mosquitoes can translate to resistance in both adults and larvae, further reducing the number of available chemicals for use against larvae. Thus, there is a need to explore new chemical control tools that will circumvent existing insecticide resistance via new modes of action, while also remaining safe to use near humans and animals. The isoxazolines and meta-diamides present relatively new chemical classes, with distinct modes of action from chemicals currently used against mosquitoes, with the added benefit of a favorable mammalian toxicity profile. The purpose of this study was to assess the comparative toxicity of the isoxazolines afoxolaner, fluralaner, and fluxametamide as well as the meta-diamide broflanilide against Aedes aegypti, Culex quinquefasciatus, and Anopheles quadrimaculatus larvae. These species represent important current and historical vectors that have negatively impacted global public health and are commonly used to generate efficacy data toward EPA registrations of mosquitocides. Fluralaner was the most toxic of the tested insecticides being over 100-fold more toxic than spinosad, a commonly used mosquito larvicide. In susceptible Cx. quinquefasciatus, fluralaner was over 1000-fold more toxic compared to spinosad. Anopheles quadrimaculatus was the least sensitive to all tested insecticides but the isoxazolines and broflanilide were still more toxic than spinosad. Some cross resistance was observed to broflanilide and fluxametamide in a multi-insecticide resistant strain of Cx. quinquefasciatus. Our data suggests that the isoxazolines and meta-diamides should be considered for development as mosquito larvicides because of their superior toxicity compared to spinosad and because of their human and animal safety profiles.