Mosquitoes Evolve Resistance to Widely Used Insecticides

WHO:

WRAL - Martha Burford Reiskind, associate professor of biological sciences at North Carolina State University, is a corresponding author of the studies.

WRAL - Keith Brown, owner of Mosquito Shield of Wake County, is involved in mosquito control efforts.

WHAT:

Phys.org - Mosquitoes are rapidly activating enzymes against common insecticides, making mosquito management increasingly difficult.

WRAL - Two studies tracked the emergence of a genetic mutation associated with resistance to pyrethroids, a class of insecticides.

WRAL - In 2023, resistance-associated mutations appeared in 84% of residential blocks sampled, and 39% of the mosquitoes carried the mutation.

WRAL - Preliminary data from 2025 show a slight increase in resistance among mosquitoes.

WHERE:

WRAL - The studies were conducted in Wake County, North Carolina.

WRAL - The highest rates of resistance were found in older neighborhoods with higher property values in Wake County.

WHEN:

WRAL - Researchers found no mosquitoes carrying the mutation in samples collected in 2016 and 2017.

WRAL - The first resistant mosquitoes were detected in a small cluster in 2018.

WRAL - The studies reported findings from 2023 and preliminary data from 2025.

WHY:

WRAL - The evolution of resistance is attributed to the repeated use of insecticides, which creates selection pressure on mosquito populations.

WRAL - The mutation indicates that mosquitoes are building resistance, which could complicate public health responses during disease outbreaks.

HOW:

WRAL - Mosquito Shield treats properties every 12 to 21 days, alternating among pyrethroids, a proprietary blend containing natural oils, and other products.

WRAL - The company uses insect growth regulators, mosquito-control stations, and larvicides to target different stages of the mosquito life cycle.

WRAL - Researchers are studying how resistant the mosquitoes are in practice and whether they carry multiple mutations.

(UPDATED July 29, 2026 07:57 UTC)

Researchers from North Carolina State University have found that mosquitoes are rapidly developing resistance to common insecticides, complicating management efforts in Wake County. Two studies revealed that in 2023, a significant 84% of residential blocks sampled showed resistance-associated mutations, with 39% of mosquitoes carrying these mutations, and preliminary data from 2025 indicates a slight increase in resistance. The evolution of this resistance is linked to the repeated use of insecticides, prompting local mosquito control efforts, including treatments every 12 to 21 days, to adapt their strategies in response to these findings.