Maharashtra: 50,000 weevils released in Panvel’s Wadale Lake to control invasive weed

The Panvel civic body said the biological-control process will take time and is expected to progress gradually. Pic/PMC

The Panvel Municipal Corporation (PMC) has released another 50,000 Cyrtobagous salviniae weevils into the historic Wadale Lake to control the spread of Salvinia molesta, an invasive floating weed that has affected the waterbody, an official statement said on Tuesday.

The second phase of the biological-control programme is being carried out jointly by the PMC and the ICAR-Directorate of Weed Research, Jabalpur.

The initiative is being implemented following directions from Panvel Mayor Nitin Patil and Municipal Commissioner Mangesh Chitale.

Weevils used as natural weed control

According to the PMC, in the first phase, 20,000 weevils were released into Wadale Lake on May 7, 2026.

It said that the conditions in the lake have been favourable for the insects, allowing them to reproduce naturally and increase their population.

Cyrtobagous salviniae primarily feeds on Salvinia molesta. The approach therefore offers a targeted method of controlling the invasive weed while reducing the need for chemical treatment, the official statement said.

The Panvel civic body said the biological-control process will take time and is expected to progress gradually.

Officials expect the weed to start changing colour, becoming yellowish 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 by around November 7, 2027.

Focus on lake's ecological balance

Deputy Municipal Commissioner Dr Vaibhav Vidhate said reducing the invasive weed could improve water circulation and help restore Wadale Lake's ecological balance.

The initiative is also expected to create a more suitable environment for migratory birds and other aquatic species.

The civic body said the programme is aimed not simply at removing the weed, but at protecting the lake's natural ecosystem and biodiversity through a scientific and environmentally friendly approach.