Polymeric macroporous formulations for the control release of mosquitocidal Bacillus sphaericus ISPC-8

Area of Science:

• Environmental Science
• Biotechnology
• Materials Science

Background:

• Mosquito-borne diseases necessitate effective and sustainable control methods.
• Bacillus sphaericus ISPC-8 is a potent mosquitocidal agent, but its field application is limited by environmental stability.
• Developing controlled-release formulations can enhance the efficacy and longevity of microbial larvicides.

Purpose of the Study:

• To develop and characterize novel bio-polymeric formulations for controlled release of Bacillus sphaericus ISPC-8.
• To evaluate the persistence and efficacy of these formulations against Culex quinquefasciatus larvae.
• To assess the protective effect of the formulations against environmental factors like UV-B and pH.

Main Methods:

• Synthesis of macroporous polymeric matrices using natural substrates (agarose, alginate, cellulose, cotton, cork powder) and magnetite nanoparticles.
• Morphological characterization of matrices, including porosity, pore distribution, and permeability.
• Controlled degradation studies over 4 weeks.
• Bioassays to determine larvicidal activity persistence against Culex quinquefasciatus larvae.
• Assessment of spore viability and toxin inactivation under UV-B and varying pH conditions.

Main Results:

• Polymeric matrices exhibited 85-90% porosity, uniform pores, high permeability, and controlled degradation (19-30% in 4 weeks).
• Unformulated B. sphaericus ISPC-8 retained only 54% larvicidal activity after 7 days, with complete loss by 35 days.
• Agarose-alginate immobilized formulations maintained significant larvicidal activity (45%) even after 35 days.
• Formulations provided substantial protection to spores and toxins against UV-B and pH inactivation compared to unformulated spores.

Conclusions:

• Biodegradable macroporous polymeric formulations enable controlled release of Bacillus sphaericus ISPC-8.
• These formulations significantly enhance the persistence and efficacy of mosquitocidal activity.
• The developed formulations show great potential for sustainable and effective mosquito control programs.