Harvard Study Reveals Rapid Evolutionary Insecticide Resistance in South American Malaria-Transmitting Anopheles Darlingi Mosquitoes

Harvard researchers sequence 1,000+ mosquito genomes, revealing that South American malaria vectors are evolving resistance to insecticides at a genomic level.

By: AXL Media

Published: Mar 27, 2026, 7:52 AM EDT

Source: Information for this report was sourced from Harvard T.H. Chan School of Public Health

Genetic Breakthrough in South American Vector Biology

A landmark study led by the Harvard T.H. Chan School of Public Health has provided the first comprehensive genomic map of Anopheles darlingi, the primary mosquito species responsible for malaria transmission in South America. Published in the journal Science, the research involved the sequencing of 1,094 complete genomes, marking a significant departure from previous studies that relied on limited genetic markers. This high-resolution approach has allowed scientists to observe the evolutionary dynamics of a species that supports the persistence of over 600,000 annual malaria cases across Brazil, Colombia, and Venezuela. According to lead author Jacob Tennessen, understanding these biological shifts is essential for blocking disease transmission and preventing the global spread of drug-resistant malaria strains.

Unexpected Evolution of Insecticide Resistance Genes

The most striking revelation of the genomic analysis is the widespread evolution of genes related to insecticide resistance across six South American nations. Previously, such resistance was only documented sporadically in Anopheles darlingi, as the region has not seen the same intensive vector-control spraying campaigns as other continents. The research team found these genetic adaptations in diverse environments, including forests, wetlands, and urban centers. Tennessen suggests that this resistance may not be a response to public health interventions but rather a side effect of heavy insecticide use in the agricultural sector, which inadvertently exerts selection pressure on the mosquito populations.

Regional Genetic Divergence and Environmental Adaptation

The study identified significant genetic differences between mosquito populations in neighboring countries, such as Guyana and Venezuela. This extensive divergence indicates that Anopheles darlingi is a highly adaptable species, well-poised to pivot its biological makeup in response to environmental changes. By analyzing specimens from 16 distinct locations, the researchers demonstrated that the species maintains a deep reservoir of genetic variety. This flexibility makes the mosquitoes harder to kill using standardized methods and suggests that local environmental factors, such as mining or farming practices, play a dominant role in shaping the specific resistance profiles of differe...