The invasion of aquatic plants in urban wetlands is a global issue that affects the ecological functionality of lagoons, rivers, and estuaries.
In Resistencia, Chaco, an interdisciplinary team led by the HeCoB Laboratory (CONICET-UNNE) is making progress on the first biological control initiative in warm wetlands in South America, using native insects as biocontrollers of water lettuce (Pistia stratiotes).
A shared problem across the continent
From the United States to El Salvador, invasive vegetation challenges traditional management methods.
- In Louisiana, control programs barely manage to contain the spread of aquatic weeds
- In El Salvador, Lake Suchitlán is almost completely covered by invasive plants
- In Resistencia, urban lagoons have coverages of up to 45% of water lettuce, as in the Argüello and Francia lagoons
These species thrive in eutrophicated waters, where the excess of nutrients —resulting from effluents and pollution— transforms native plants into invaders.
Native insects as ecological allies
Experimental trials confirm the potential of two herbivorous species to reduce the invasive biomass.
The HeCoB team identified two insect species that, in tests carried out in CECOAL pools, effectively feed on water lettuce, reducing its size and coverage.
Currently, work is being done on mass breeding, a preliminary step to an experimental release planned for mid-2026.
“It would be the first experience of biological control in subtropical wetlands in the country,” highlights Dr. Celeste Franceschini, project director.
Institutional articulation and international cooperation
The project links science, public management, and global biological control networks.
Organizations participating include:
- FUEDEI (Argentina)
- Centre for Biological Control (South Africa)
- Louisiana State University (USA)
From the Municipality of Resistencia, Ing. Sergio Vich emphasizes that the proliferation of aquatic weeds affects critical functions such as flood mitigation, biodiversity conservation, and the provision of recreational spaces.
Therefore, the creation of a municipal biofactory is being promoted to scale up the production of control insects.
The Capybaras: local experience and community commitment
A municipal team with 30 years of experience supports the transition towards more sustainable management.
The work group “Capybaras”, created in 1995, has faced the plant invasion with artisanal tools and physical effort. Its leader, Rito Prado, celebrates the project:
“We are proud of our work, but we support biological control as a lasting alternative.”
Manually removing water lettuce can take over a month, but in a few days, the “little buds” reappear, highlighting the need for comprehensive solutions.
Restoring wetlands: a bet on urban resilience
The lagoons of Resistencia offer key ecosystem services, but require active protection.
From HeCoB, Lic. Sabrina Bertucci and Dr. Lara Sabater explain that eutrophication alters water quality and promotes plant proliferation. Biological control, on the other hand, emerges as a natural, economical, and environmentally sustainable alternative.
“Argentina is pioneering this approach, and we want to add this project as a model case in subtropical wetlands,” concludes Franceschini.
