Links

Bacillus thuringiensis subspecies israelensis, commonly referred to as Bti, is a bacterium found naturally in soils. Since 1982, it has been used

successfully worldwide as a biological pest control agent to

combat mosquitoes and blackflies.

How Does Bti Work?

During the spore-forming stage of its life cycle, the Bti bacterium produces a protein crystal which is toxic only to mosquito and blackfly larvae.  These microscopic crystals are ingested by insect larvae when they are feeding. In the alkaline environment of the susceptible insect’s digestive system, the crystals are dissolved and converted into toxic protein molecules that destroy the walls of the insect’s stomach. The insect usually stops feeding within hours and dies within days.

How is Bti Used?

Bti is applied directly to the water where mosquito and blackfly larvae are found. The bacteria are suspended in the water where the larvae will ingest it. None of the products containing Bti may be applied to treated, finished drinking water for

human consumption.

Are There Health Concerns Related

to the Use of Bti?

Bti poses little threat to human health through either handling products directly or being exposed to them indirectly, e.g., during a provincial or municipal mosquito control program. To activate Bti toxins, alkaline conditions that exist only in            

certain insects’ digestive systems must be present.  The acidic stomachs of humans and animals do not activate Bti toxins. There have been no documented cases involving toxicity or endocrine disruption potential to humans or other mammals

over the many years of use in Canada and around the world. Studies have shown that even if Bti spores are ingested or inhaled, they are eliminated without any adverse health effects.

The fact that Bti is a naturally occurring, widely distributed organism in the environment means that the average person would have multiple exposures

to this bacterium throughout their lifetime, even if they never came in contact with a formulated product.

Home | Board of Health | Contact Us

Copyright © Flathead City-County Health Department. All rights reserved.
Last Updated 4/25/03