Pests eating up Mumbai’s ‘evergreen’ mangroves

PEST CONTROL

forests, which should flourish during the monsoon months of August and September, have been wearing a dry, skeletal look across the Mumbai Metropolitan Region (MMR) for more than a decade.

Ideally, this should not happen: these trees are evergreen, which means they never shed their leaves; there is usually plenty of water during these months as Mumbai receives adequate rain; and, mangrove plants grow only near water bodies, in inter-tidal areas or wetlands.

So, what is causing this mass shedding?

Puzzled by the phenomenon, and worried if it may affect the forests, the mangrove cell of the Maharashtra forest department reached out to Bengaluru’s Institute of Wood Science and Technology (IWST). “We were clueless about why the trees looked completely dry, and why its skeletal structure was visible during this time of the year,” said N Vasudevan, additional principal chief conservator of forest, state mangrove cell. IWST’s preliminary results, based on field visits to mangrove forests in Airoli and Ghansoli, along the Thane-Vashi

MUMBAI:Mangrove

creeks, found 14 pests — seven species of caterpillars (Lepidoptera), two beetle species (Coleoptera), a leaf miner (Lepidoptera), two snail species and three grasshoppers (Orthoptera) — were responsible for the destruction. The study, called ‘Development of integrated pest management strategies against major defoliating pests of mangroves in Mumbai Metropolitan Region’ , said four mangrove species were affected the worst — grey mangrove (Avicennia marina), Indian mangrove (Avicennia officinalis),

Apple mangrove (Sonneratia apetala) and White mangrove (Sonneratia alba). While the plants can regenerate in a few months, their reproduction cycle gets severely impaired, IWST scientists said.

“These pests, during the larval stage (when juveniles become adults), feed mainly on the leaves and sometimes the bark,” said N Mohan Karnat, additional principal chief conservator of forests, group co-ordinator (research), Institute of Wood Science and Technology, Bengaluru.