Here’s how Bti, the larvicide DNCC imported to control dengue, works
While Bti is used across Singapore, various cities in India, Malaysia, Thailand, the Philippines and many US states, experts in Bangladesh are sceptical about its effectiveness
It was yet another Saturday morning at The Business Standard newsroom when one of our readers called the online hotline.
"Hello, Is this TBS? I have some queries about an article on 'DNCC applying Bti to control dengue' you published earlier. Is it safe for humans?" a concerned voice asked.
Amid a multitude of blank calls, the concern sounded genuine. When he was rest assured that the larvacide does not have any adverse effects on humans, at least according to the report, he reacted with a sigh of relief.
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Although the conversation didn't last long, the question lingered, especially if you look at it from a layman's perspective.
And why not. It was not too long ago when two minors died from pesticide poisoning in the capital's Basundhara, where a pest control service was carried out last June.
Recently, Dhaka North City Corporation (DNCC) imported five tonnes of insecticide bacteria called Bacillus Thuringiensis Israelensis (Bti) in July as part of its efforts to control dengue.
On Thursday (3 August), Dhaka North Mayor Md Atiqul Islam, during a discussion on dengue prevention activities of the city corporation, said an expert team from Singapore will hold a conference with the health department of the city corporation on Friday (4 August) and Saturday (5 August) to provide guidance on the proper mixing and application of the pesticide.
Here The Business Standard tries to shed some lights on what we could know by far about the city corporation's new weapon against mosquito.
What is Bti?
Bti is a biological or naturally occurring bacterium found in soils.
According to the United States Environmental Protection Agency (EPA), Bti contains spores that produce toxins that specifically target and only affect the larvae of the mosquito, blackfly and fungus gnat. EPA approves the insecticide.
The US Department of Health and Human Services mentions on its website Bti produces toxins when mosquito larvae eat it.
Bti comes in many forms, including tablets, briquettes, pellets, granules or liquid. DNCC imported Bti tablets.
The best way to get rid of dengue is always to destroy its habitat by emptying out exposed water containers or keeping them covered. But it is not always possible to do so, and Bti comes into play in these cases.
This insecticide can be added to standing water and to containers that cannot be emptied out, covered or turned over each week. It can be used in rain barrels, ornamental ponds (garden ponds), fountains, septic tanks and pools.
"Bti can be used around homes in areas and containers where water can collect, such as flower pots, tires, and bird baths. Bti can also be used to treat larger bodies of water like ponds, lakes and irrigation ditches," according to EPA.
Is it harmful?
Bti is not toxic to people. The US CDC still found no evidence of Bti making anyone sick.
As a matter of fact, Bti has also been found safe for pets, aquatic life (making it safer to use in ponds) and even other insects such as honeybees.
Bti can be used in residential, commercial and agricultural settings without the risk of any harm. Even some organic farming operations in the US use Bti, according to CDC.
However, it needs to be used as directed. If applied as directed, BTI can kill mosquito larvae without causing any harm to food crops or water supplies.
Certain Bti products can even be used by pest control professionals in drinking water storage containers, CDC mentions. However, not all Bti are approved by EPA for drinking water containers.
Will it be effective?
While Bti is used across Singapore, various cities in India, Malaysia, Thailand, the Philippines many US states, including Massachusetts, Pennsylvania, Maryland and Michigan, experts in Bangladesh are sceptical about its effectiveness.
Talking to The Business Standard, Dr Be-Nazir Ahmed, former director of disease control at the Directorate General of Health Services, earlier said Bti is different from the existing method being used to control mosquito in Dhaka.
"Its biggest advantage is that it is a biological solution. Mosquito control is possible if it can be applied properly," he said.
"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.
Final notes
Importing Bti and incorporating the pesticide in Dhaka North's ongoing fight against dengue is definitely a step forward. However, city dwellers too need to keep in mind that city corporations alone cannot destroy all the mosquito habitats.
No matter how effective Bti turns out, mass awareness is the most crucial segment of the fight against dengue. As experts say, eliminating any standing water, even the tiniest amounts, is the best way to destroy Aedes habitats.
In addition to emptying pots around our houses, we can also make it into a habit of upturning any small pots like coconut shells or single-use plastic cups with standing water, whenever we notice them on roadsides, especially during the monsoon season.
