The Panvel Municipal Corporation has released 50,000 Cyrtobagous salviniae weevils into Wadale Lake as part of the second phase of a biological-control programme targeting Salvinia molesta, an invasive floating weed that has affected the historic waterbody.
The initiative is being carried out jointly by the civic body and the ICAR-Directorate of Weed Research, Jabalpur, according to an official statement. The programme is being implemented following directions from Panvel Mayor Nitin Patil and Municipal Commissioner Mangesh Chitale.
The first phase began on May 7, 2026, when 20,000 weevils were released into the lake. The PMC said conditions at Wadale Lake have been favourable for the insects, allowing them to reproduce naturally and increase their population before the latest release.
Cyrtobagous salviniae primarily feeds on Salvinia molesta. The civic body said using the weevils provides a targeted method of controlling the invasive weed while reducing the need for chemical treatment. Officials have cautioned that the biological-control process will take time and will progress gradually.
According to the PMC’s timeline, the weed is expected to begin changing colour to yellow and then dark chocolate-brown by February 7, 2027. It is expected to be progressively eliminated over the following nine months, with the process likely to be completed around November 7, 2027.
Deputy Municipal Commissioner Dr Vaibhav Vidhate said reducing the invasive weed could improve water circulation and help restore Wadale Lake’s ecological balance. The civic body said the intervention is also expected to create a more suitable environment for migratory birds and other aquatic species.
The PMC said the programme is intended not only to remove the weed but also to protect the lake’s natural ecosystem and biodiversity through a scientific and environmentally friendly approach. The next milestones identified by the civic body are the gradual colour change in the weed from February 2027 and the projected completion of the control process by November 2027.
