Related Experiment Video
Updated: Aug 11, 2026
A Bacterial Oral Feeding Assay with Antibiotic-Treated Mosquitoes
Published on: September 12, 2020
[Clostridium bifermentans serovar malaysia, a new anaerobic bacterium pathogen to mosquito and blackfly larvae]
H de Barjac1, M Sebald, J F Charles
1Unité des Bactéries entomopathogènes, Institut Pasteur, Paris.
Abstract:
A strain of Clostridium bifermentans individualized as serovar malaysia (C.b.m.) according to its specific H antigen is toxic to mosquito and blackfly larvae when given orally. The toxicity occurs in sporulated cells which contain, in addition to spores, proteinic parasporal inclusion bodies and feather-like appendages; the amino acid content of the inclusion bodies is similar to that of Bacillus thuringiensis serovar israelensis (B.t.i.) and B. sphaericus crystals. The toxicity to Anopheles stephensi is as high as that of B.t.i. and the best strains of B. sphaericus. Culex pipiens is somewhat less susceptible, and Aedes aegypti much less. Pure parasporal inclusion bodies, isolated by ultracentrifugation on sucrose gradients, are highly toxic to mosquito larvae. The larvicidal power is destroyed by heating at 80 degrees C or by treatment with 50 mM NaOH. It is preserved by freeze-drying. The innocuity to mice of the sporulated cells is shown by different routes of administration: force-feeding, percutaneous, subcutaneous, intraperitoneal or intravenous injections. The potential for the biological control of mosquito and blackfly larvae is suggested.
Insights
Clostridium bifermentans serovar malaysia exhibits potent larvicidal activity against mosquito and blackfly larvae. Its toxic parasporal inclusion bodies offer a promising avenue for biological control agents.
Area of Science:
- Microbiology
- Toxicology
- Entomology
Context:
- Clostridium bifermentans serovar malaysia (C.b.m.) possesses unique H antigens.
- Sporulated C.b.m. cells contain proteinic parasporal inclusion bodies and feather-like appendages.
- The amino acid composition of these inclusion bodies resembles that of Bacillus thuringiensis israelensis (B.t.i.) and Bacillus sphaericus crystals.
Purpose:
- To investigate the larvicidal toxicity of C.b.m.
- To characterize the toxic components and their stability.
- To assess the safety of C.b.m. for non-target organisms.
Summary:
- C.b.m. is toxic to mosquito and blackfly larvae, with toxicity concentrated in sporulated cells containing parasporal inclusion bodies.
- Larvicidal potency against Anopheles stephensi is comparable to B.t.i. and B. sphaericus.
- Pure inclusion bodies are highly toxic, with activity lost upon heating or NaOH treatment but preserved by freeze-drying.
- Sporulated cells demonstrated no toxicity in mice via various administration routes.
Impact:
- C.b.m. represents a potential new biological control agent for mosquito and blackfly larvae.
- The findings contribute to the understanding of bacterial toxins for pest control.
- Innocuity to mammals suggests a favorable safety profile for environmental application.
Related Concept Videos
00:58Symbiosis
01:30Bacterial Phylum Spirochaetes
01:24Bacterial Phylum Tenericutes