Mumbai has lost 238 rain trees to a pest attack in the last couple of months, stated a report compiled by the garden department of the Brihanmumbai Municipal Corporation (BMC).
As per the report, a pest called Mealybug infested more than 50 per cent of those trees which have died. It revealed that 500 rain trees across the city were infested by the pest, but after taking a host of measures, the civic body was able to save 262 of them.
The rain trees in Zone IV, which includes Veera Desai Road, MG Road in Goregaon (West) and Link Road in Malad (West) among others, suffered the most with 180 trees infested by the pest. The BMC was able to revive
only 120 of them. It was followed by Zone III (BKC Road, CST Road MIDC Road, SV Road, Khar) where 119 trees were infested by the pest and only 64 could be revived. Out of the 13 trees infested in in Zone VI (LBS Road, 90 feet Road) only five trees were revived.
"Initially, we thought that it was a temporary attack, which will be washed out in heavy rains, but the Mealybug population continued to increase rapidly, attacking more and more trees," said a garden department official.
Alarmed by the rise in population of the pest, BMC submitted samples of Mealybugs with infested leaves and branches to the bio-control lab of entomology department, College of Agriculture in Pune. The samples were also submitted to the National Bureau of Agriculturally Important Insects (NBAII) in Bangalore, for identification of the pest and control measures. The results said that the dysmicocus neobrevipes beardsley species of Mealybugs had attacked the rain trees in the city.
A number of experts such as Fogro Gomes, head of entomology department, Konkan Krishi Vidyapeeth, Dapoli, and IIT-B expert Ganeshan also visited the sites, collected samples and gave their recommendations.
"Currently, we have started following the Integrated Pest Management (IPM) techniques, which include biological, chemical and mechanical measures," said Vijay Hire, superintendent of gardens.
He explained: "We are using 5,500 Australian Lady Bird Beetles, which are predator insects that feed directly on Mealybugs. We have procured them from the College of Agriculture, Pune and NBAII, Bangalore." He added that the department is also contemplating dusting and spraying of bio-pesticides, comprising parasite fungus, which too feeds on the pest.
"We are also carrying out trimming of infested branches and destroying them immediately. We will also apply pulp of neem leaves around the tree trunks, since it is said to act as a repellent to the pest," said the official.
About Mealybugs
The Mealybugs suck cell sap from the leaves and also inject poisonous saliva into them, thereby killing the trees. Eventually, leaves and branches of the tree start falling off and the tree dries up. Civic officials say the attack was first seen on rain trees along roads, but later the bug started attacking isolated trees too.
Factors causing attack
1. Transporting infested plants from outside the city
2. The pest got a favourable environment with a huge number of host plants, mostly rain trees
3. Planting a single tree species in a single line and cables hanging over trees helps transmitting the pest rapidly from one plant to another
4. Use of same tree trimming/cutting tools
5. A white wooly cover on Mealybugs protects them from predators and pesticides
Short-term measures
1. Procuring bio-control agents and chemical pesticides in large scale
2. Inviting expert entomologists regularly for examining trees
Long-term measures
1. Appointing expert entomologist or declaring the pest control officer of the ward as a nodal officer for controlling pests
2. Applying strict quarantine measures at all entry points to the city
3. Removing cables hanging over trees
4. Checking sapling stock for infestation in private nurseries
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