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Bti (Bacillus thuringiensis israelensis)

Bti stands for Bacillus thuringiensis israelensis, a non-reproducing bacterium discovered in the soil of Israel's Negev Desert in 1977. When the mosquito eats the Bti spores and crystals, they enter the larvae's stomach and dissolve. Due to the specific Ph of the mosquito’s midgut, these crystals produce a toxin that is fatal to the mosquito, but has little or no impact on other aquatic life. Commercial manufacturers have produced several different formulations to provide a variety of application methods.

Larviciding with Bti

Liquid Bti can be used in hand held pump cans, back pack sprayers, hydraulic sprayers or truck mounted sprayers. It delivers a mixed amount of Bti at a predetermined rate, according to label directions and present larval conditions. The Bti is mixed with water to ensure uniform coverage. The hydraulic sprayer delivers the mixed solution to the area that has been determined to hold sufficient amounts of larvae to justify an application, <1 larvae per dip average over 5 dips. This method is used to apply Bti in larger areas along roadsides and other accessible areas.

A granular type of Bti can be used in different ways. It can be broadcast by hand or using a backpack, where the applicator can access areas not available to truck mounted equipment or aerial applications due to a heavy tree cover (canopy). Aircraft, either fixed wing or helicopter, are used to deliver it to large, widespread areas inaccessible to any truck or hand application because of size or location.

Bti is considered practically non-toxic. These applications are typically made in isolated areas, away from most residential areas. Therefore the applications present a minimal risk to the general population.


Pesticide Label:

Vectobac G ()

Safety Data Sheet (SDS):

Vectobac G ()

One new formulation of Bti is the controlled release granule (CRG) formulation put out by Four Star Microbial products. This formulation releases Bti at a pre-determined rate, allowing for longer control. CMMCP will be performing field trails of this new formulation in 2014 in areas prior to egg hatching, called pre-hatch. By applying before the larvae are active, we can cover more areas before the larvae molt into pupae, and then hatch out as adults. Please check for results of these field trails at this link:


Pesticide Label:

Bti CRG ()

Safety Data Sheet (SDS):

Bti CRG ( 81k)

Pesticide Information Profile/Bt

EPA: Controlling Mosquitoes at the Larval Stage



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