Panvel civic body releases weevils into Vadale Lake

As part of the initiative, the civic body released cyrtobagous salviniae weevils—tiny aquatic insects that feed exclusively on the invasive Salvinia molesta weed—into the lake to naturally destroy the rapidly spreading floating plant.

PANVEL: In a first-of-its-kind ecological intervention in the Mumbai Metropolitan Region, the Panvel Municipal Corporation (PMC) on Thursday launched a biological-control campaign to clear invasive aquatic weeds choking the historic Vadale Lake, one of Panvel’s oldest and most ecologically significant water bodies.

Navi Mumbai, India - May 8, 2026:PMC launches biological-control drive to restore historic Vadale lake at Panvel in Navi Mumbai, India, on Friday, May 8, 2026. (Photo by Bachchan Kumar/ Hindustan Times) (Hindustan Times)

As part of the initiative, the civic body released cyrtobagous salviniae weevils—tiny aquatic insects that feed exclusively on the invasive Salvinia molesta weed—into the lake to naturally destroy the rapidly spreading floating plant.

Spread across nearly 25 acres near the old Mumbai-Pune highway in Old Panvel, Vadale Lake is believed to be nearly 400 years old. Environmentalists often describe it as the “ecological lung” of Panvel because of its role in supporting biodiversity, groundwater recharge and urban ecological balance.

Over the past few years, the rapid spread of the invasive salvinia weed has severely impacted the lake’s ecological balance. The weed forms dense floating carpets over the water surface, drastically reducing oxygen levels and sunlight penetration, threatening the fish populations, lotus blooms and nearly 32 species of local and migratory birds that the lake supports.

Nadkarni and other activists such as Ranjana Sadolikar met municipal commissioner Mangesh Chitale in December 2025 and warned that the unchecked spread of the invasive weed was threatening the lake’s ecosystem and bird habitat. The activists proposed the use of the weevils, noting that the insects feed only on the salvinia weed without harming native plants or aquatic life.

“Vadale Lake is an important environmental and heritage asset for Panvel,” said Chitale. “Through scientific intervention and coordination with research institutions, we are attempting a sustainable and permanent solution.” Added Panvel mayor Nitin Patil, “It is cost-effective and environmentally safe. We expect Vadale Lake to gradually regain its original ecological character.”

The project is being implemented in collaboration with the Indian Council of Agricultural Research and the ICAR-Directorate of Weed Research in Jabalpur. Dr Archana Anokhe, scientist at the latter institute, said the results would show gradually.

“Within three to six months, brown patches will start appearing in the areas where the weevils are released,” she said. “In heavily infested lakes like Vadale, the process can take around 15 to 18 months for substantial clearing and sinking of the weed cover, after which open water will become visible again.”