The Dhaka South City Corporation (DSCC) in a meeting in 2021 decided to utilize environmentally friendly Bacillus thuringiensis israelensis (Bti) bacteria to control Aedes mosquitoe breeding. However, two years have passed, and there is no visible progress in implementing this decision.
Experts say if this technology had been deployed two years ago, the spread of dengue would have been significantly reduced by now.
The DSCC's pesticide selection committee initially approved the experimental use of Bti technology during a meeting held on October 11, 2021. Unfortunately, the decision did not come into effect at that time.
Dhak TribuneLater, on February 5, the committee reaffirmed the same decision in another meeting.
Traditional methods
Currently, the DSCC continues to use temephos larvicide each morning to combat mosquito larvae, while malathion and delta methylene are used for fogging in the afternoons.
During applying larvicide to destroy mosquito larvae, 60 millilitres of temephos is used with 40 litres of water. Malathion and deltamethrin, used in killing adult mosquitoes or fogging, are mixed with diesel and used in fogger devices.
DSCC Chief Health Officer Dr Fazle Shamsul Kabir said: "Our committee of entomologists and experts meets twice a year. According to the recommendations of those meetings, all measures including prescribing medicines were taken. But now temephos has proven to be quite effective in larvicide activities. So we are not thinking about changing it right now.”
Regarding the delay in implementing the earlier decision, he added: "We are heavily occupied with the current dengue situation, leaving no opportunity to test any new technology. Nevertheless, we plan to adopt this technology at an appropriate time."
What do experts have to say?
Entomologists said Bti is a type of bacteria that naturally destroys mosquito larvae without causing harm to people or water when applied.
Entomologist Dr Manzur Ahmed Chowdhury said: "Bti is a natural, affordable and sustainable solution. It serves as a low-level toxic pesticide of microbial origin. The bacteria produce potent toxins that halt insect feeding. Consequently, the larvae perish without consuming any food."
According to the US Centers for Disease Control and Prevention, Bti is available in various formulations, including pills, liquids, bullets and powders.
It can be applied to ponds, sewers, drains, ditches, or any water-holding areas like road puddles, open spaces, or containers.
The bacteria have also received approval from the US Environmental Protection Agency.
High time to replace old technology
Jahangirnagar University Zoology Department Professor Kabirul Bashar, who was present at the meeting of the DSCC's pesticide selection committee, said: “Temephos has been used in larvicide in Dhaka for a long time. However, due to prolonged usage, mosquitoes have developed a tolerance to it. Therefore, it is crucial to switch to something new.
“We believe it is best to use pesticides that are more effective, environmentally friendly and pose fewer health risks. Considering the worldwide success of Bti, I recommended its experimental use. The decision was taken in two meetings, but I am uncertain why it was not implemented later."
Meanwhile, the Dhaka North City Corporation (DNCC) has already completed the process of implementing Bti technology by taking a decision earlier this year.
DNCC Public Relations Officer Mokbul Hossain said: "We have completed preparations to implement this technology. We brought the technology from Singapore. It is now awaiting unloading at the port. We can start implementing this technology in the first week of August.”