Amazonian Entomopathogenic Fungi Show Promise in Mosquito Control

Researchers at the Instituto Leônidas & Maria Deane – Fiocruz Amazônia have tested a new biocontrol strategy against Anopheles aquasalis, a key mosquito vector for malaria in coastal South America. The study examined whether local fungal isolates collected from the Amazon rainforest could reduce mosquito survival rates.

Two fungal species—Trichoderma harzianum and Penicillium citrinum—proved effective, reducing mosquito lifespan significantly within days of exposure. These findings support their potential as entomopathogenic agents in future mosquito control programmes.

Why does this matter?

Malaria remains a public health issue, with 263 million cases in 83 countries in 2023. Considering the goal of malaria elimination worldwide, researchers have been committed to search new strategies for vector control. Insecticides are widely used as a vector control for malaria. However, their effectiveness has been threatened due to the evolution of mosquitoes resistant to them. Therefore, new strategies tackling the mosquitoes’ resistance against insecticides are essential.

Image credits: Centers for Disease Control and Prevention's Public Health Image Library

Testing fungi from the Amazon

The researchers used four fungal strains from Fiocruz’s Amazon collection: P. citrinum, P. oxalicum, T. harzianum and T. virens. Mosquitoes were exposed to fungal spores at different concentrations and monitored for up to 25 days.

P. citrinum and T. harzianum consistently reduced survival. In both cases, mosquitoes exposed to high spore concentrations died significantly faster than control groups. For T. harzianum, effects were observed even at the lowest tested concentration.

Scanning electron microscopy confirmed fungal growth on mosquito surfaces, especially legs and joints. These regions are vulnerable due to thinner cuticles and more pores.

A safe, targeted biocontrol tool?

The fungi were originally isolated from forest soils and decaying vegetation in the Brazilian Amazon. Using local fungal strains may help avoid unintended ecological impacts, and the study confirmed that T. harzianum was the only microorganism recovered from exposed mosquitoes, suggesting targeted action and low contamination risk.

Previous work on Trichoderma species has shown they can secrete chitinases and other enzymes that break down insect cuticles. For Penicillium, the mode of action may involve mycotoxins with neurotoxic effects.

Next steps

While promising, the researchers caution that field trials are needed to evaluate long-term effectiveness and ecological safety. Factors like humidity, fungal persistence, and mosquito immune responses could all influence outcomes.

Still, this study marks the first time these two Amazonian fungi have demonstrated entomopathogenic activity against this species of mosquitoes (An. aquasalis). With further testing, they could become part of an integrated vector management approach that helps reduce malaria transmission without relying on chemical pesticides.