Breakthrough Research on Mosquito Control in Brazil

The recent publication in Acta Tropica details a significant advancement in understanding how populations of the southern house mosquito, Culex quinquefasciatus, respond to innovative vector control tools. Led by researchers including Bashir Alsharif, Maria Alice Varjal de Melo-Santos, Rosângela Maria Rodrigues Barbosa, Luca Facchinelli, Philip J. McCall, and Constância Flávia Junqueira Ayres, the study evaluates susceptibility in a Recife, Brazil population to CARBAPAINT 10, a propoxur-based insecticidal paint, alongside a skirting-based application method originally developed for Aedes aegypti control.

Published online ahead of the August 2026 issue, the work highlights the mosquito's complete susceptibility in laboratory assays and promising results in simulated room environments. This matters because Culex quinquefasciatus serves as a primary vector for lymphatic filariasis in parts of Brazil and contributes substantially to nighttime biting nuisance in urban settings.

Understanding Culex quinquefasciatus and Its Public Health Role

Culex quinquefasciatus, commonly known as the southern house mosquito, thrives in tropical and subtropical urban environments. Females prefer to feed on birds and mammals, including humans, at night and rest indoors afterward, a behavior classified as endophily. In Recife, this species has long been associated with transmission of Wuchereria bancrofti, the parasite responsible for lymphatic filariasis, a debilitating disease that can lead to severe swelling and disability if untreated.

Unlike Aedes aegypti, which drives daytime transmission of dengue, Zika, and chikungunya, Culex quinquefasciatus has received less targeted large-scale control attention in Brazil despite its abundance. Historical integrated programs in Recife during the 1990s combined source reduction, biological control with Bacillus sphaericus, and community engagement to suppress breeding sites. The new study builds on that foundation by testing a passive, long-lasting intervention that could complement existing efforts.

The Insecticidal Paint Technology: CARBAPAINT 10

CARBAPAINT 10, manufactured by Inesfly, consists of a water-based acrylic paint containing 1.0% propoxur, a carbamate insecticide, formulated with microencapsulation for prolonged release. Propoxur disrupts the nervous system of insects by inhibiting acetylcholinesterase. The product has demonstrated efficacy against a range of pests, including mosquitoes, cockroaches, and flies, and is particularly noted for performance against pyrethroid-resistant populations.

Application as a thin skirting band along the lower walls near the floor represents a departure from traditional indoor residual spraying that covers entire wall surfaces. This targeted approach reduces the amount of insecticide used while focusing on resting sites preferred by certain mosquito species. The black color variant tested in the study proved especially effective, likely due to visual attraction or contrast that encourages landing.

Study Methodology and Key Findings

Researchers collected Culex quinquefasciatus from Recife and subjected them to standard World Health Organization cone bioassays. Exposure to CARBAPAINT 10 resulted in 100% mortality within the observation period, confirming full susceptibility in this local population.

Free-flight experiments in an experimental room simulated real-world conditions. Skirting boards treated with the paint were installed, and mosquitoes were released to assess contact and mortality. Black-painted skirting achieved approximately 70% mortality, significantly outperforming white-painted skirting at around 30%. Efficacy was higher against non-blood-fed females compared to those that had recently fed, reflecting differences in resting behavior and energy reserves.

These outcomes suggest the skirting method, designed primarily for Aedes aegypti that often rest lower on walls, can incidentally provide substantial control of Culex quinquefasciatus as well. The dual impact strengthens the case for broader adoption in areas where both species coexist.

Photo by arda tutkun on Unsplash

Implications for Integrated Vector Management in Brazil

Recife and surrounding areas in Pernambuco state continue to manage residual lymphatic filariasis transmission alongside arbovirus outbreaks. A tool that simultaneously addresses multiple vectors offers operational efficiencies for public health programs. Reduced insecticide volume through skirting application aligns with principles of judicious pesticide use and may lower environmental and human exposure risks compared to full-wall treatments.

Community acceptance could improve because the intervention leaves most wall surfaces untouched, preserving aesthetics while delivering protection. The study authors note that impacting all human-biting mosquitoes enhances the likelihood of sustained public support for such measures.

Author Contributions and Institutional Context

The collaborative team draws expertise from Brazilian institutions such as the Oswaldo Cruz Foundation (Fiocruz) and international partners at the Liverpool School of Tropical Medicine. Bashir Alsharif contributed field and laboratory work tied to his affiliations in Brazil. The Brazilian co-authors bring deep knowledge of local mosquito ecology and prior control programs in Recife. UK-based researchers provided specialized input on novel delivery systems and experimental design.

Such partnerships exemplify how global networks accelerate translation of laboratory findings into field-relevant tools. The open-access publication in Acta Tropica ensures wide accessibility for researchers, program managers, and policymakers.

Broader Context of Insecticide Resistance and Novel Tools

Many mosquito populations worldwide exhibit resistance to common insecticide classes, including pyrethroids used in bed nets and sprays. Propoxur-based formulations like CARBAPAINT 10 provide an alternative mode of action. Microencapsulation extends residual activity, potentially lasting months rather than weeks, which reduces the frequency of reapplication.

Previous evaluations of the same paint against Anopheles and Aedes species have shown strong results. The current work extends that evidence base to Culex quinquefasciatus, supporting its versatility across major vector genera.

Future Research Directions and Scalability

While laboratory and semi-field data are encouraging, larger-scale field trials in occupied homes across different Recife neighborhoods would strengthen evidence for programmatic rollout. Monitoring for any emerging resistance, durability of the paint under tropical humidity and cleaning practices, and cost-effectiveness analyses remain priorities.

Integration with other strategies—such as larval source management, sterile insect technique pilots, and improved housing design—could create robust, multi-layered defenses. The skirting method's low visibility may also facilitate acceptance in densely populated urban settings where full spraying faces logistical or social barriers.

Photo by Francesco Ungaro on Unsplash

Relevance to Academic and Research Careers

Studies like this underscore demand for skilled professionals in medical entomology, vector biology, and public health implementation science. Universities and research institutes in Brazil and internationally seek candidates with expertise in insecticide evaluation, mosquito behavior, and community-based interventions. Opportunities exist in government agencies, international organizations, and private-sector developers of vector control products.

Early-career researchers can draw inspiration from the multidisciplinary approach demonstrated here, combining molecular susceptibility testing, behavioral assays, and applied public health perspectives.

Conclusion and Outlook

This publication marks an important step toward more efficient, acceptable tools for controlling Culex quinquefasciatus alongside other urban mosquitoes. The demonstrated high susceptibility and effective skirting delivery method in Recife populations suggest strong potential for real-world impact. Continued investment in such innovations supports Brazil's ongoing efforts to reduce vector-borne disease burdens while advancing global knowledge on sustainable vector management.

Readers interested in the full details can access the original article at https://www.sciencedirect.com/science/article/pii/S0001706X26002275.