Mosquitoes make DSCC residents’ lives miserable

Nazmul Hasan's family had adopted every measure they had heard of to save themselves from mosquitoes. They applied repellents and lit mosquito coils at their Lalbagh house in the evening. Also, they never forgot to hang mosquito nets before sleeping and used electric bats to kill the insects.

"Yet, all these measures don't save us from mosquito bites," a frustrated Nazmul told The Daily Star recently.

Nazmul's frustration is shared by the residents of Dhaka South City Corporation (DSCC), who continue to suffer from the mosquito menace -- especially Culex mosquitoes -- as DSCC had failed to take adequate measures timely, they said.

There has been a rise in the Culex mosquito population just after winter, due to high temperatures and humid condition, late but excessive rainfall last year, and lack of proper attention to destroy mosquito hotspots, said entomologists.

Dr Manjur Chowdhury, an entomologist and former president of Zoological Society of Bangladesh, said one of the main reasons for the proliferation of mosquitoes this year is heavy rainfall during October and November last year.

"Excessive rainfall at the beginning of winter helped create breeding grounds for mosquitoes at different places. When the water in drains and abandoned waterbodies gets gradually polluted, it becomes a breeding place for Culex mosquitoes," he said.

A large percentage of shallow drains in the city were deepened in the last couple of years, and as a result, they now collect more water. Covered with concrete slabs or footpaths, these drains get clogged with garbage and have been gradually polluted. Staffers of the city corporation cannot reach these places to spray larvicide properly, he explained.

Dr Manjur said the two city corporations did not take proper measures timely, as they were busy controlling Aedes mosquito population, at a time when they should have focused on Culex mosquitoes.

Prof Kabirul Bashar of Jahangirnagar University said when the amount of pollutants increases, the number of Culex mosquitoes also increases.

The pollutants, mainly comprising organic matter, act as food for Culex mosquito larvae, said Bashar, also an entomologist.

The temperature in this year's February was higher than that of previous years. High temperature is favourable for mosquito breeding, he added, suggesting that the mosquito control drive should have been thorough.

An official of DSCC's health department recently said it will take some time to control the Culex mosquito population at areas where their numbers are already high. They are cleaning waterbodies gradually.

There are 569 bighas of waterbodies in DSCC, which need to be cleaned, the official added.

DSCC Chief Executive Officer ABM Amin Ullah Nuri said they are emphasising on using both larvicide and adulticide.

Mentionable, DSCC's drives against Culex mosquitoes go on all year round, and the situation has somewhat improved in the last few days.

'USING FROGS A WRONG DECISION'

DSCC on March 16 released 10,000 small frogs at a cost of TK 20,000 in 10 waterbodies under its jurisdiction on experimental basis.

Earlier, it released ducks and tilapia fish in 10 other waterbodies to curb the proliferation of mosquitoes.

Experts, however, think such measures are a waste of time and money, as they would not reduce the mosquito population.

"Ducks and frogs would not be effective, as they do not eat mosquito larvae. If authorities release guppy fish on a regular basis, it would be more effective," said Dr Manjur.

The small frogs will become adults after a month, and then they might be of some use. But by that time, it will be the season of Aedes mosquitoes, which become active during daytime, while the frogs become active at night, he said.

Asked, the chief executive officer said they released the frogs on an experimental basis.

He said they will have to try controlling the mosquito population through biological methods, gradually reducing water pollution, as spraying insecticide is harmful for health.