Dhaka North imports Bti bacteria to intensify mosquito control

The Dhaka North City Corporation has imported insecticide bacteria Bacillus thuringiensis serotype israelensis (Bti) from Singapore through a private company as part of its efforts to control dengue, a mosquito-borne viral infection that has created a significant public health concern in the country.

By using this biological larvicide, the authorities aim to reduce the mosquito population and mitigate the transmission of dengue in the city, as the menace has already claimed the lives of more than 200 people this year.

A shipment of around five tonnes of Bti arrived at Chattogram port earlier this week, Brig Gen AKM Shafiqur Rahman, chief health officer at Dhaka North, told The Business Standard.

"We hope to use it in different North City areas next week after a trial," he said, adding, "We can use the Bti brought in the first phase for at least 4-5 months. If it proves effective, it will be used throughout the year."

Two experts from the island nation will arrive here to train employees and mosquito control workers of the city corporation on how to use the insecticide bacteria, according to Dhaka North.

Bti is a biological larvicide that effectively targets the larvae of mosquitoes, fungus gnats, and black flies. When applying the gnat insecticide to aquatic habitats where these pests breed, it can control their populations while remaining safe for humans, pets, livestock, and beneficial insects.

Dr Be-Nazir Ahmed, former director of disease control at the Directorate General of Health Services, told TBS, "Bti is different and another weapon in Dhaka's mosquito control. Its greatest advantage is that it is a biological solution. Mosquito control is possible if it is applied properly."

"But Bti will not be very effective in dengue control in this situation. It is more effective against Culex mosquitoes. If the larvicide does not reach the point of origin of the Aedes mosquitoes, it will not be effective. To get rid of dengue, the habitat of Aedes must be destroyed," he added.

Every year, the city corporation takes new initiatives, such as crash programmes and combing operations, to control mosquitoes, but these efforts have had little effect.

Such week- or month-long campaigns are mainly to kill mosquitoes. However, the fact that these campaigns with complex names are fruitless is evident from the horrors of dengue.

Besides, city dwellers have seen ducks, frogs, and guppy fish reared in water reservoirs and even tried to kill flying mosquitoes by planting sedges to attract birds. Apart from this, Dhaka North has also identified the sources of mosquitoes and spread medicine in inaccessible water bodies using drone technology.

Delegations have also gone abroad several times for training in mosquito control. Last January, after returning from Miami-Dade County, USA, Mayor Atiqul Islam said that the two city corporations in Dhaka have been trying to kill mosquitoes in the wrong way for so long.

Dhaka North hopes to benefit from the application of Bti drugs through larviciding, as all previous methods to control mosquitoes have failed.

Experts say Bti is natural, affordable, and sustainable. This bacterium is being used in various countries, including Singapore and India's Kolkata. It is mainly used as a low-toxic insecticide of microbial origin, including for stomach poisoning. The bacteria can produce large amounts of toxins, which stop the insect from eating.

Dhaka North Deputy Chief Health Officer Md Golam Mostafa Sarwar told TBS that different countries produce this Bacteria. Singapore, various cities in India, Malaysia, Thailand, and the Philippines have been successful in controlling mosquitoes using Bti. The climate of Bangladesh is similar to that of those countries.

"In Kolkata, some companies also produce Bti. A company from Kolkata also approached us here to sell Bti but it was brought from Singapore as it was cheaper," he added.

According to experts, Bti can be sprayed over water bodies such as ponds, lakes, rivers, and streams. It is used to kill developing mosquito larvae by being applied to standing water where those larvae are found.

Bti can be used around homes in areas and containers where water can collect, such as flower pots, tires, and bird baths. It can also be used to treat larger bodies of water like ponds, lakes, and irrigation ditches.

Mixing 15 grams of medicine in 100 litres of water and sprinkling it over an area of 1.5 square kilometres gives good results. The medicine will be effective for 30 days.

But if it gets into the eyes, it can cause visual disturbances and skin damage. Bti has no toxicity to people and is approved for use for pest control in organic farming operations, they added.