DNCC has been using the tablet-form Novaluron since October last year in an attempt to bring the Culex mosquitoes under control. A total of 629 mosquito breeding grounds were selected. The insecticide was applied in lakes, canals and other water bodies in Gulshan, Banani, Uttara, Mirpur and other selected places. But these places now have that the highest density of mosquitoes.

From Monday DNCC resumed its normal anti-mosquito drive. Mayor Atiqul Islam said that this drive to destroy larva and mosquitoes in 10 zones will continue for 10 days.

Applying Novaluron to water

According to DNCC, 480kg of Novaluron was procured at the cost of Tk 4,50,5544 from England in September last year. So far 250kg has been used. It was purchased from the company Russell IMP in England and supplied by Tech International to DNCC by means of tender. Each Novaluron tablet weighs one gram. One tablet is used for 10 litres of water.

When applying Novaluron, DNCC's deputy chief health officer Golam Mostafa Sarwar had told Prothom Alo that this chemical destroys the upper coating of the larva (chitin), killing the larva before it can metamorphose as a mosquito. He said from the beginning this was being used in the lake next to Uttara sectors 11 and 12.

However, former general secretary of Uttara sector 12 welfare association Sharif Shantu, speaking to Prothom Alo over mobile phone two days ago, said, "We have never sees so many mosquitoes before. It is scary, the way they swarm all over."

When DNCC began using Novaluron, I told them clearly that this would not work. I was against this from the very beginning and that is why many DNCC officials were annoyed with me. But look at the situation now. It has been proven that the product is ineffective
Entomologist Kabirul Bashar of Jahangirnagar University

The parks of Uttara sectors 11 and 12 would always throng with local residents in the evenings, but a visit to the area on Sunday Prothom Alo correspondent saw the parks vacant. The local people say that they no longer come to the parks because of the mosquitoes. They stay at home in the evenings, using mosquito coils, sprays and electric bats to kill the mosquitoes.

Why was Novaluron ineffective?

Under arrangement of DNCC, associate professor of Jahangirnagar University's zoology department, Tahmina Akhter, supervised a three-month experiment with Novaluron. It was said then that this insecticide could destroy the larva of insects which had chitin in their bodies. As mosquito larva contained chitin, Novaluron would be able to curb the breeding of the mosquitoes. It was also said that the substance would remain effective in water up till 90 days.

If that was so, there should have been no Culex in the city now. But reality is quite the contrary. Whether it is the high-end areas of Gulshan, Banani and Uttara, or the relatively lesser developed areas of Mirpur, Mohammedpur, Mohakhali, Khilkhet, or even the newer areas of the city corporation like Beraid, Dumuni, Uttarkhan and Dakkhikhan, the mosquitoes are everywhere. The city residents feel this is the worse ever mosquito menace they can remember.

Secretary general of Gulshan Society, Shukla Sarawat, told Prothom Alo, "We are benumbed. I have never seen so many mosquitoes in my lifetime. It is as if man has been defeated by mosquitoes."

She said she had no idea that the product Novaluron had been used in Gulshan Lake.

Jahangirnagar teacher Tahmina Akhter, speaking to Prothom Alo on Monday, said, "When I tested the product, I told the city corporation back then that its formulation would not be effective in our context. The moment it was placed in the water, it sank to the bottom. If it floated or if arrangements could be made to keep it afloat, then perhaps it would be effective in ditches or closed water bodies."

Entomologist Kabirul Bashar of Jahangirnagar University told Prothom Alo, "When DNCC began using Novaluron, I told them clearly that this would not work. I was against this from the very beginning and that is why many DNCC officials were annoyed with me. But look at the situation now. It has been proven that the product is ineffective. If it had been effective, there would not be so many mosquitoes now."

He went on to say, "Novaluron comes into effect as it spreads. But our water bodies and ditches are large and so polluted that the product cannot spread. The filth in the water doesn't allow the chemical to spread and so it doesn't work. That is why the country's climate and situation has to be taken into account when selecting a product."

DNCC's chief executive officer Selim Reza told Prothom Alo that there had been some shortcomings in the application of Novaluron. But the product was seen to be effective. He said Novaluron was not suitable for all drains and ditches. Even so, it was used wherever possible and some results had been yielded.

Supplier Tech International's coordinator Tanveer Ahmed said that Novaluron was used in the UK, Canada and Singapore. He told Prothom Alo, after three months of observing its effect, Novaluron was given clearance. He said the city corporation, IEDCR under the health ministry and Jahangirnagar University had separately tested it. After it was seen to be fully effective in the lab and in the field, then it was decided for use. It is manufactured in England.

Concerning these comments of the Jahangirnagar teachers, Tanveer Ahmed said, if the substance floated, it perhaps would just float and accumulated in one place. Then what? He said that Novaluron was effective in the cleanest to the filthiest water. So why was there such a mosquito menace in the city?

He said, it seems the city corporation did not apply the substance in the right place or in the right amount. Unless it is used properly, it will not be effective.

DNCC mayor Atiqul Islam, when asked about the matter, said that the corporation's chief health officer Md Zobair Rahman would be able to explain.

The chief health officer said, "The substance was used in accordance to the instructions of the city corporation's entomologists. There may be different views. But I do not think that the substance is ineffective."

He went on to say, "I am not dismissing anyone's opinion. But as the city corporation has been engaged in this task, it has both the experience and the knowledge."

Md Zobair Rahman said that the chemical had been wrapped in a net and tied to a bamboo in the water so that it did not float away.

*This report appeared in the print and online editions of Prothom Alo and has been rewritten in English by Ayesha Kabir