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Emerging Trends in Larvicide Resistance: Implications for Mosquito Control Symposium II

Emerging Trends in Larvicide Resistance: Implications for Mosquito Control Symposium II

Emerging Trends in Larvicide Resistance: Implications for Mosquito Control Symposium II

177 - Larval Resistance to S-methoprene Observed for the First Time in the Twin Cities Metropolitan Area, Minnesota

Wednesday, March 25, 2026
5:25 PM - 5:30 PM PDT
Location: B115
Abstract: Metropolitan Mosquito Control District(MMCD) has been protecting the residents of the Twin Cities Metropolitan Area from the disease and annoyance associated mosquitoes, black flies, and ticks since 1958. This protection is provided by implementing a wide-sweeping control program based around extensive larvicidal usage partnered with very little adulticidal applications. These larvicidal applications have relied heavily on the use of the insect growth regulator, s-methoprene for decades. In recent years the prevalence of resistance to larvicidal molecules has been studied and identified in other areas across the Midwestern United States. In 2025, MMCD staff initiated a study in partnership with Northshore Mosquito Abatement District (NSMAD) to assess Culex pipiens populations around the Twin Cities. Studies indicated one population of pipiens carried a resistance ratio of roughly, 55. This is the first time that larvicidal resistance has been observed in the state of Minnesota. These findings have lain the groundwork for further studies in 2026 to further assess Culex populations in the Twin Cities metropolitan area.