Characterization of six highly mosquitocidal Bacillus thuringiensis strains that do not belong to H-14 serotype

Area of Science:

• Microbiology
• Entomology
• Biochemistry

Background:

• Bacillus thuringiensis (B.t.) is a soil bacterium known for producing insecticidal crystal proteins.
• Mosquito-borne diseases pose significant public health challenges, necessitating effective vector control strategies.
• Identifying novel B.t. strains with potent larvicidal activity is crucial for developing sustainable mosquito control methods.

Purpose of the Study:

• To identify and characterize novel Bacillus thuringiensis strains with high toxicity against key mosquito species.
• To compare the larvicidal and hemolytic activities of new strains with established mosquitocidal B.t. strains.
• To analyze the protein profiles and immunological relationships of crystal toxins from the identified strains.

Main Methods:

• Screening of six novel B.t. strains for larvicidal activity against Aedes aegypti, Anopheles stephensi, and Culex pipiens.
• Determination of larvicidal and hemolytic activities.
• Electrophoretic analysis of crystal protein profiles.
• Immunological comparison with B.t. israelensis (B.t.i.) polypeptides.

Main Results:

• Four B.t. serovars (thompsoni, malaysiensis, canadensis, jegathesan) and two auto-agglutinating strains demonstrated high toxicity to mosquito larvae.
• Five of the six new strains exhibited larvicidal and hemolytic activities, crystal proteins, and toxin genes similar to B.t. israelensis.
• One strain, B.t. jegathesan 367, displayed a unique larvicidal activity pattern and a distinct protein profile.

Conclusions:

• Novel B.t. strains possess significant potential for mosquito larvicidal control.
• B.t. jegathesan 367 represents a distinct strain with potentially novel insecticidal properties.
• Further research into B.t. jegathesan 367 could lead to new tools for integrated vector management programs.