Bacillus thuringiensis israelensis
Bacillus thuringiensis israelensis (Bti) is a naturally occurring bacterium that has revolutionized pest control with its environmentally friendly and highly effective approach. Bti specifically targets…
Strength
1 x 10⁸ CFU per gram / 1 x 10⁹ CFU per gram
Benefits
Targeted Pest Control
Specifically targets and controls mosquito larvae, reducing mosquito populations.
Environmental Safety
Non-toxic to humans and other non-target organisms, safe for aquatic ecosystems.
Effective and Specific
Highly effective against mosquito larvae with minimal impact on other organisms.
Biodegradable
Breaks down naturally in the environment, leaving no harmful residues.
FAQ
Q1. Is Bacillus thuringiensis israelensis safe for use near humans and pets?
A: Yes, Bti is non-toxic to humans, pets, and beneficial organisms like bees and fish.
Q2. How does Bti compare to chemical pesticides?
A: Unlike broad-spectrum chemical pesticides, Bti specifically targets larvae, minimizing collateral damage to the environment.
Q3. Can Bti be used in organic farming?
A: Absolutely. Bti is certified for organic use and aligns with sustainable agricultural practices.
Q4. What pests does Bti target?
A: It is highly effective against mosquito larvae, black flies, fungus gnats, and aquatic dipterans.
Future Directions
Enhanced Bioremediation: Genetic engineering could further optimize Bti for improved pollutant degradation and pest control.
Industrial Scaling: Scaling Bti production for broader applications in mosquito control and agriculture.
Integrated Pest Management Innovations: Expanding Bti’s role in sustainable pest control strategies for diverse ecosystems.
Bacillus thuringiensis israelensis is a powerful tool for sustainable pest management. With its precision targeting, environmental safety, and versatility, Bti offers an eco-friendly alternative to chemical pesticides. Whether combating vector-borne diseases, managing agricultural pests, or restoring ecosystems, Bti is an indispensable part of integrated pest management programs.
Learn more about how Bacillus thuringiensis israelensis can transform your pest control strategy. Contact us today.
Scientific References
(Rudd et al., 2023) – Describes the complex protein compartmentalization in Bti’s parasporal body and its role in larval toxicity.
(Stalinski et al., 2016) – Investigates Cry toxin-specific receptor responses and resistance development in Aedes aegypti.
(Boisvert et al., 2007) – Reviews two decades of Bti use in Canada for mosquito control and its environmental safety.
(Tan et al., 2012) – Field trial showing reduction in dengue cases following Bti treatment in Malaysia.
(Gunasekaran et al., 2002) – Demonstrates long-lasting larvicidal activity of sustained-release Bti formulations in polluted habitats.
(Becker et al., 2018) – Reports no resistance development in Aedes vexans after 36 years of Bti application.
(Allgeier et al., 2018) – Evaluates biochemical responses in amphibians exposed to Bti, relevant for non-target safety assessments.
(Nasser et al., 2021) – Describes the development of hydrogel-based Bti formulations for sustained larvicidal activity.
(Tilquin et al., 2008) – Provides evidence of Bti persistence in natural mosquito habitats post-application.
Mode of Action
Mode of Action – Bacillus thuringiensis subsp. israelensis (Bti)
Bacillus thuringiensis subsp. israelensis (Bti) is a spore-forming, Gram-positive bacterium that produces insecticidal proteins during sporulation. These proteins accumulate in a parasporal crystalline inclusion body and include four major protoxins: Cry4Aa, Cry4Ba, Cry11Aa, and Cyt1Aa. Together, they form a highly potent and synergistic toxin complex specifically targeting the larval stages of dipteran insects, including Aedes, Culex, and Anopheles mosquitoes, as well as blackflies and fungus gnats.
1. Ingestion and Activation
When Bti spores and crystals are ingested by susceptible insect larvae, the alkaline pH (~10–11) of the insect midgut solubilizes the crystal proteins. This allows the protoxins to be processed into their active toxin forms by midgut proteases.
2. Binding to Midgut Epithelial Receptors
The activated Cry toxins (Cry4Aa, Cry4Ba, and Cry11Aa) bind to specific glycoprotein receptors—such as aminopeptidases, alkaline phosphatases, and cadherin-like proteins—on the brush border membrane of midgut epithelial cells. This binding is receptor-specific, accounting for the narrow host range and high target specificity of Bti.
3. Pore Formation and Cell Lysis
Upon binding, Cry toxins insert into the membrane and oligomerize to form transmembrane pores. These pores disrupt the osmotic balance of epithelial cells, causing cell swelling, lysis, and ultimately midgut epithelium rupture. This leads to leakage of gut contents into the hemocoel and septicemia.
4. Cyt1Aa Synergism
Cyt1Aa functions through a complementary mechanism. It binds to membrane lipids in a receptor-independent manner, forming pores itself and acting as a synergist for Cry toxins. Cyt1Aa improves Cry toxin binding by serving as a surrogate receptor and prevents resistance development by targeting different membrane components.
5. Mortality and Environmental Decay
The physiological effect is rapid—larvae typically stop feeding within hours and die within 24 to 48 hours. Spores released into the insect hemocoel germinate, contributing to systemic infection and accelerating mortality. Importantly, Bti toxins are biodegradable, and their specificity means they pose no significant risk to non-target organisms, including humans, mammals, fish, amphibians, and most beneficial insects.
6. Resistance Management
The multi-toxin composition of Bti is a critical feature for resistance prevention. The presence of both Cry and Cyt toxins, each with distinct binding sites and modes of membrane disruption, makes the development of resistance in field populations exceedingly rare, even under prolonged use.
Additional Info
Bacillus thuringiensis israelensis (Bti) is a Gram-positive, spore-forming bacterium that has transformed pest management. Known for its precision and environmental safety, Bti specifically targets insect larvae, such as mosquitoes, black flies, and fungus gnats, while leaving non-target organisms unharmed. Its role in integrated pest management (IPM) has made it a cornerstone for sustainable and ecologically sensitive pest control.
Explore our microbial solutions for sustainable pest management here.
How Bacillus thuringiensis israelensis Works
Bti produces insecticidal crystalline proteins (ICPs), including Cry4A, Cry4B, Cry11A, and Cyt1A, which are lethal to insect larvae. The mechanism includes:
Ingestion: Larvae consume Bti spores and toxins.
Activation: In the alkaline midgut environment of larvae, the toxins become active.
Binding: The toxins bind to gut receptors, forming pores in the gut lining.
Larval Death: The resulting gut cell destruction and septicemia cause death.
This targeted mechanism ensures safety for pollinators, mammals, and aquatic organisms.
Applications of Bacillus thuringiensis israelensis
Mosquito Control: Effective in managing mosquito larvae in standing water, urban drainage, and sewage systems.
Targets mosquito species such as:
Aedes spp. (dengue, Zika, chikungunya vectors)
Anopheles spp. (malaria carriers)
Culex spp. (West Nile virus vectors)
Black Fly Management: Applied in rivers and streams to control black fly larvae, reducing diseases like river blindness and livestock infections.
Agricultural and Greenhouse Pest Control
Targets pests such as:
Fungus gnats (Bradysia spp.) that harm plant roots.
Non-biting midges and aquatic dipterans that disrupt ecosystems.
Offers a safer alternative to chemical pesticides, protecting crops and beneficial insects.
Environmental Applications
Used in bioremediation efforts, reducing pest populations in contaminated water bodies and restoring ecological balance.
Advantages of Bacillus thuringiensis israelensis
Environmentally Friendly: Specifically targets pests without harming non-target species, preserving biodiversity.
Resistance Management: Can be combined with other biological agents like Bacillus sphaericus to minimize resistance development.
Cost-Effective Production: Advanced fermentation methods, including the use of sewage sludge as a substrate, make Bti production sustainable and affordable.
Versatility: Effective in various settings, from mosquito control in urban areas to pest management in agriculture and greenhouses.
How to Use Bacillus thuringiensis israelensis
Mosquito Breeding Sites:
Apply granules or liquids directly to standing water.
Frequency: Reapply every 7–14 days during peak breeding seasons.
Agricultural Use:
Use as a foliar spray or soil drench for greenhouse crops.
Black Fly Control:
Apply in fast-flowing rivers and streams to target larvae.
Dosage & Application
Soluble Liquid: 4100 ITU per milligram / 1 x 10⁸ CFU per gram
Foliar Application
Dose: 0.5 - 1 ml / square metre of water body
1 Acre dose: 2 – 4 L
1 Ha dose: 5 – 10 L
Apply on water bodies. Use lower doses for cleaner water and higher doses for polluted water bodies. Apply at 1-2 week intervals.
Foliar Application Method
Mix Bacillus Thuringiensis – Israelensis at recommended doses in sufficient water and spray on the water body.
Apply at intervals of 1-2 weeks.
Other Uses: It can be used for seed care. Mix 10g Bacillus subtilis with 10g crude sugar in sufficient water to make a slurry. Coat 1kg of seeds, dry in shade, and sow / broadcast / dibble in the field. Do not store treated / coated seeds for more than 24 hours.
Note: Do not store Bacillus Thuringiensis – Israelensis solution for more than 24 hours after mixing with water.
