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Micro-lipid-droplet encapsulation of Bacillus thuringiensis subsp. israelensis delta-endotoxin for control of
Abstract:
The crystal delta-endotoxin of Bacillus thuringiensis subsp. israelensis is less toxic to larvae of Anopheles freeborni than to larvae of Aedes aegypti. However, when solubilized crystal was used, larvae from both species showed similar sensitivities. This effect presumably was due to the differences in feeding behavior between the two mosquito larvae when crystal preparations are used. A procedure is described whereby both crystal and solubilized B. thuringiensis subsp. israelensis toxin were emulsified with Freund incomplete adjuvant, with retention of toxicity. The use of Freund incomplete adjuvant also allowed one to assay the solubilized toxin at a low nanogram level. Furthermore, coating the toxin with lipophilic material altered the buoyancy of the toxin and reversed the sensitivities of the two mosquito larvae toward the B. thuringiensis subsp. israelensis toxin. This difference in buoyancy was determined by using an enzyme-linked immunosorbent assay that was specific for the toxic peptides. These data indicate that economically feasible buoyant formulations for the B. thuringiensis subsp. israelensis crystal can be developed.
Insights
Bacillus thuringiensis israelensis (Bti) crystal toxin showed different toxicity to mosquito larvae based on formulation. Buoyant formulations may offer cost-effective mosquito control solutions.
Area of Science:
- * Molecular biology and entomology
- * Biopesticide development and application
Background:
- * Bacillus thuringiensis subsp. israelensis (Bti) crystal delta-endotoxin exhibits differential toxicity to mosquito larvae.
- * Larval feeding behavior influences toxicity of crystal preparations.
Purpose of the Study:
- * To investigate the impact of Bti toxin formulation on mosquito larval toxicity.
- * To explore the development of effective and economical Bti formulations for mosquito control.
Main Methods:
- * Comparison of toxicity between crystal and solubilized Bti toxin against Anopheles freeborni and Aedes aegypti larvae.
- * Emulsification of Bti toxin with Freund incomplete adjuvant to maintain toxicity and enable low-level assays.
- * Lipophilic coating of toxin to alter buoyancy and assess impact on larval sensitivity using enzyme-linked immunosorbent assay (ELISA).
Main Results:
- * Solubilized Bti toxin showed similar sensitivity in both mosquito species, unlike crystal preparations.
- * Freund incomplete adjuvant allowed for low nanogram level assaying of solubilized toxin.
- * Altering toxin buoyancy via lipophilic coating reversed larval sensitivities, indicating buoyancy's role.
Conclusions:
- * Larval feeding behavior significantly influences the toxicity of Bti crystal preparations.
- * Buoyancy is a critical factor in Bti toxin efficacy against different mosquito species.
- * Development of economically feasible buoyant Bti formulations for mosquito control is promising.