The choices people make to control mosquitoes in their own backyards may be helping some of those mosquitoes survive the very insecticides meant to kill them, according to two new studies from North Carolina State University.
The studies focus on the tiger mosquito ( Aedes albopictus ), an invasive species that is now common across much of the eastern United States and a major day-biting mosquito in the Southeast. The mosquito thrives in urban and suburban environments, where it breeds in small containers and other places where water collects.
In North Carolina, households may hire private mosquito-control companies or apply insecticides themselves to reduce nuisance biting in their yards. The studies suggest those individual decisions, repeated across neighborhoods, can create conditions that favor the evolution of insecticide resistance.
“Homeowners with money will pay to spray for mosquitoes, which selects for localized resistance,” said Martha Burford Reiskind, associate professor of biological sciences at NC State and corresponding author of the papers. “Over time, as more and more resistance builds up in the population, it will become harder to control populations. The insecticides will no longer be as effective.”
The research centers on pyrethroids, a class of insecticides commonly used to kill adult mosquitoes. Pyrethroids are relatively inexpensive and considered among the safer insecticides for use around people, pets and homes. In places where mosquito-borne diseases are common, pyrethroids can play an important role in limiting transmission. In North Carolina, however, they are often used to reduce nuisance biting.
The researchers found that mosquitoes in Wake County developed and maintained mutations associated with pyrethroid resistance. One study used archived mosquito samples from 2016 to 2024 to track how quickly one of those mutations appeared and spread. The other examined whether socioeconomic factors helped predict where insecticide resistance was most common.
The researchers found no resistant mosquitoes in their Wake County samples from 2016 and 2017. The first resistant mosquitoes appeared in 2018 in a small cluster. By 2023, resistance had spread widely across the sampling area: researchers found resistance-associated mutations in 84% of sampled residential blocks, and 39% of sampled mosquitoes carried the mutation.
“We see the rapid rise of pesticide resistance in places like South America and Asia where there is continuous spraying in some countries,” Burford Reiskind said. “But resistance driven by private mosquito control is novel in the contiguous U.S., to our knowledge.”
The second study found that resistance was higher in neighborhoods with higher total property values, which researchers used as a proxy for homeowner wealth. The researchers did not directly measure household insecticide use, but the findings suggest that wealthier households may be more likely to use private mosquito-control services or other chemical insecticide treatments, creating localized selection pressure for resistance.
The researchers used a genetic screening method to identify a mutation in the mosquito’s genome. This mutation is associated with “knockdown resistance,” or kdr, which can reduce mosquitoes’ sensitivity to pyrethroid insecticides. “This mutation is often the first to show up when there’s insecticide resistance,” Burford Reiskind said.
Tiger mosquitoes are aggressive daytime biters and can transmit viruses including dengue, Zika and chikungunya, as well as dog heartworm. The studies focused on insecticide resistance rather than disease transmission, but the findings matter because resistance can reduce the effectiveness of tools used to control mosquitoes when public health risks arise.
Michael Reiskind, professor of entomology at NC State and a co-author of both papers, says the next step is to expand sampling across a broader range of neighborhoods.
“We want to make a better effort to get a diversity of neighborhoods, age and wealth in order to extend our findings and see whether they work at different housing densities and wealth levels,” Reiskind said.
The findings point to the need for integrated pest management strategies that reduce reliance on chemical insecticides alone. For homeowners, that includes targeting mosquitoes earlier in their life cycle by removing or cleaning anything that can hold rainwater, where mosquito larvae develop.
“A reliance on just chemical insecticides is never the best way to control a pest,” Burford Reiskind said. “We really want to integrate pest management practices that look at the whole lifecycle of the pest.”
The paper on the emergence and spatial distribution of resistance appears in Parasites & Vectors . Jennifer Baltzegar, former graduate student and postdoctoral researcher at NC State, is the paper’s first author. Baltzegar was part of an NSF-funded graduate training program in the Genetic Engineering and Society Center. She is now faculty at Augusta University.
The paper on socioeconomic predictors of resistance appears in Royal Society Open Science . Cole Butler, an NC State Ph.D. graduate in biomathematics who is now a postdoctoral researcher at the University of Georgia, is the paper’s lead author. Co-authors on both papers include Jessica Ding, Emily MX Reed, Zachary Brown, Michael Reiskind and Martha Burford Reiskind of NC State.
The research was supported by seed funding from NC State’s Genetics and Genomics Academy and Global One Health Academy.
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Note to editors: Abstracts follow.
“Emergence and spatial distribution of knockdown resistance in a suburban population of Aedes albopictus”
Authors: Jennifer F. Baltzegar1,2, Cole D. Butler1,3, Jessica Y1. Ding, Chay M. Beeson1, Emily MX Reed1, Michael H. Reiskind1 and Martha O. Burford Reiskind1
1. North Carolina State University; 2. Augusta University; 3. University of Georgia
Published: June 27, 2026 in Parasites & Vectors
DOI: 10.1186/s13071-026-07519-6
Abstract : Aedes albopictus is a major vector of arboviral diseases and is often targeted by pyrethroid-based mosquito control in residential areas. While knockdown resistance (kdr) mutations are well documented in Ae. aegypti, their emergence in Ae. albopictus has been less studied, particularly in suburban environments where insecticide application is often uncoordinated. Understanding the temporal and spatial dynamics of resistance evolution in this context is critical for preserving the effectiveness of public health interventions. We conducted longitudinal sampling of Ae. albopictus populations in Wake County, North Carolina, from 2016 to 2024. Using a novel allele-specific PCR melt curve assay, we genotyped 2,273 mosquitoes at the F1534S locus in the voltage-gated sodium channel gene. Resistance allele frequencies were calculated annually and mapped across the county for three key years – 2016, 2018, and 2023 – representing the pre-emergence, initial detection, and widespread phases of resistance development. Selection and dominance were estimated using the Wright-Fisher Approximate Bayesian Computation algorithm for locus F1534S. The F1534S resistance allele was first detected in 2018 at a central, affluent neighborhood. By 2023, the allele had spread throughout the sampling region, with the highest frequencies near the site of first detection. Resistance allele frequency peaked at 0.36 in 2023, accompanied by an increase in heterozygous and homozygous resistance genotypes. Temporally sampled sites showed consistent trends in rising resistance, with all temporally-sampled locations harboring resistance genotypes by 2022. The resistance allele was found to be under high selection pressure and partially recessive in this population. Our findings reveal rapid emergence and spatial expansion of the F1534S kdr allele in Ae. albopictus populations in a suburban setting. The pattern of spread suggests strong local selection pressure, likely driven by residential pyrethroid use. These results highlight the need for proactive resistance monitoring and integrated management strategies that address private-sector contributions to insecticide selection pressure.
“Socioeconomic predictors of knockdown resistance in the globally invasive tiger mosquito Aedes albopictus”
Authors : Cole D. Butler1,2, Jessica Y. Ding1, Zachary Brown1, Jennifer F. Baltzegar1,3, Martha O. Burford Reiskind1, and Michael H. Reiskind1
1. North Carolina State University; 2. University of Georgia; 3. Augusta University
Published: July 8, 2026 in Royal Society Open Science
DOI: 10.1098/rsos.251678
Abstract: The tiger mosquito Aedes albopictus (Skuse) is a nuisance biter and vector for many dangerous pathogens. Population control of this species primarily relies on the spraying of chemical insecticides. However, the emergence of insecticide resistance, otherwise known as knockdown resistance (kdr), jeopardizes control and is a serious threat to public health. Effectively managing resistance requires us first to understand the conditions that predict its evolution. Here, we investigate the association between total property value and the frequency of kdr in Ae. albopictus populations in Raleigh, North Carolina, USA. We hypothesized that kdr frequency correlates with total property value, because we speculate that wealthier neighborhoods apply chemical insecticides more frequently. We tested this hypothesis by sampling mosquito populations from 31 different residential blocks across the city and along a total property value gradient. Overall, we found a high frequency of kdr (39%) over a spatially heterogeneous distribution that was significantly correlated with total property value. We find evidence supporting a connection between socioeconomic factors with the rise of insecticide resistance, something not previously documented for this species. This suggests that economic interventions may be a promising approach to resistance management in this and other contexts.
Royal Society Open Science
Observational study
Cells
8-Jul-2026
We declare we have no competing interests.