Genetic Resistance to DDT Found in Malaria-Transmitting Mosquitoes Due to Historical Insecticide Use

Genetic Resistance to DDT Found in Malaria-Transmitting Mosquitoes Due to Historical Insecticide Use

(IN BRIEF) Scientists have identified the first instances of genetic mutations in Anopheles funestus mosquitoes that confer resistance to DDT, a previously widespread insecticide now banned due to environmental concerns. This discovery, made by researchers from the University of Glasgow and the Ifakara Health Institute in Tanzania, highlights a significant adaptation in this key malaria vector. The study, published in Molecular Ecology, reveals the emergence of “knock-down resistance” (kdr) linked to historical contamination from DDT stockpiles. The findings underscore the challenges posed to current malaria control strategies that heavily rely on insecticides and the potential implications of past environmental practices on modern public health.

(PRESS RELEASE) GLASGOW, 8-Oct-2024 — /EuropaWire/ — Recent research has unveiled the first documented instances of Anopheles funestus mosquitoes exhibiting genetic mutations that confer resistance to the insecticide DDT. This breakthrough finding, highlighted in a study led by the University of Glasgow in collaboration with the Ifakara Health Institute in Tanzania, points to a significant evolutionary adaptation in a key malaria vector in Eastern and Southern Africa.

The study, published in Molecular Ecology, identifies the emergence of “knock-down resistance” (kdr), a critical mechanism that pests develop in response to insecticides. The association between this newly observed mutation and DDT resistance raises alarms, especially given DDT’s historical prevalence and its current ban due to environmental concerns. The researchers suspect that this mutation may stem from historical contamination and existing stockpiles of DDT that continue to impact the local ecosystem.

In their investigation, the research team employed whole-genome sequencing across multiple mosquito populations in Tanzania to explore genetic variations within Anopheles funestus. The unexpected resistance to DDT in one particular population prompted further examination, leading to the discovery of novel kdr mutations.

Interestingly, the resistant mosquito population was collected from an area adjacent to a former DDT stockpile, suggesting that prolonged environmental exposure to the insecticide may have imposed selective pressure, fostering the development of this resistance.

Chemical insecticides remain a cornerstone of efforts to control agricultural pests and disease-carrying insects like mosquitoes. The distribution of over 2.9 billion insecticide-treated bed nets (ITNs) has significantly reduced malaria incidence, preventing an estimated 633 million cases. However, the reliance on insecticides also poses health risks and has ecological repercussions. The ongoing battle between mosquito adaptations and insecticide effectiveness presents a formidable challenge to sustainable malaria management.

Joel Odero, lead author and PhD student at the University of Glasgow’s School of Biodiversity, One Health and Veterinary Medicine, remarked, “Our findings underscore the potential risks to current malaria control strategies that depend heavily on insecticides. Understanding the development of resistance is crucial for combating malaria, a disease that continues to claim hundreds of thousands of lives, predominantly in Africa.”

Dr. Francesco Baldini from the University of Glasgow added, “This research illuminates the long-lasting and unintended impacts of historical insecticide use, illustrating how past environmental contamination can influence the evolution of vector populations and the effectiveness of modern public health initiatives.”

Fredros Okumu, associated with both the University of Glasgow and the Ifakara Health Institute, emphasized the necessity for urgent follow-up research to track the evolution of DDT resistance among vectors and explore whether similar resistance could arise in other insecticide classes currently being implemented across Africa.

The research article titled “Discovery of knock-down resistance in the major African malaria vector Anopheles funestus” can be found in Molecular Ecology.

Media Contact:

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SOURCE: University of Glasgow