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Poster Session

Poster Session

Poster Session

P21 - Comparative Evaluation of Larvicide Efficacy against Culicoides sonorensis 

Wednesday, March 25, 2026
12:15 PM - 1:45 PM PDT
Location: Hall A
Abstract: Culicoides sonorensis, biting midges are vectors of bluetongue, epizootic hemorrhagic disease, vesicular stomatitis, and Oropouche viruses, which are of veterinary and public health importance. There are limited control options for midges in the U.S., because they are generally considered a nuisance pest. However, with the recent resurgence of Oropouche virus and travel related cases in the U.S., there is a need to examine the effectiveness of larvicides on Culicoides midge populations. Here we tested six different larvicide formulations containing four active ingredients (Novaluron, Methoprene, Spinosad, and Pyriproxyfen). These active ingredients, classified as insect growth regulators (IGRs) and microbial synthetic larvicides, are primarily used in mosquito control programs. Larvicide applications to artificial midge habitats were conducted at three ecologically distinct field sites in Kansas, Texas, and Louisiana to evaluate how environmental conditions, including temperature, humidity, and substrate type, affect the efficacy of larvicides. Larval bioassays and mass spectrometry analyses were conducted to measure adult emergence and to assess the persistence of active ingredients in field trials over time, respectively. Reduction in adult emergence was observed with the first 10 days of application. Treatments containing Novaluron, Spinosad, and pyriproxyfen sustained effectiveness for 20 days post-application, while the effectiveness of Methoprene was < 10 days. These findings highlight pesticide formulations using an IGR and spinosad as the active ingredient have the potential to impact Culicoides populations and may be used to develop sustainable and regionally tailored management approaches.