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Vertebrate safety of Clostridium bifermentans serovar malaysia, a new larvicidal agent for vector control
I Thiery1, S Hamon, V C Dumanoir
1Unité des Bactéries Entomopathogènes, Institut Pasteur, Paris, France.
Abstract:
The safety of bacterial cells of Clostridium bifermentans serovar malaysia, which is highly toxic to mosquito larvae, was tested on mice, guinea pigs, rabbits, and goldfish. Inoculations of at least 1 x 10(8) cells per animal by routes recommended by World Health Organization (subcutaneous, percutaneous, inhalation, force-feeding, intraperitoneal, intravenous) and tests of subacute toxicity, anaphylactic shock, persistence in heart blood, and virulence by successive passages, were performed on mice, guinea pigs, or both. Growth was monitored for 1 mo before necropsy. Ocular irritation and skin scarification were tested with rabbits. C. bifermentans serovar malaysia did not induce any mortality or abnormal reactions in mammals at a dose 1,000 times higher than the level established by W.H.O. for the demonstration of safety. Bacterial cells are not toxic to goldfish at a dose 1,000 times higher than the LD50 for the target-mosquito larvae. We conclude that C. bifermentans serovar malaysia bacterial cells are safe for laboratory mammals and goldfish.
Insights
Clostridium bifermentans serovar malaysia, a potent mosquito larvicide, demonstrated excellent safety in mammals and goldfish. Even at high doses, it caused no adverse effects, indicating its safe use in non-target organisms.
Area of Science:
- Microbiology
- Toxicology
- Environmental Science
Background:
- Clostridium bifermentans serovar malaysia poses a significant threat to mosquito larvae.
- Assessing the safety of microbial larvicides on non-target organisms is crucial for environmental protection.
Purpose of the Study:
- To evaluate the toxicological profile of Clostridium bifermentans serovar malaysia bacterial cells.
- To determine the safety of C. bifermentans serovar malaysia for laboratory mammals and goldfish.
Main Methods:
- Mammalian safety tests included various inoculation routes (subcutaneous, percutaneous, inhalation, force-feeding, intraperitoneal, intravenous) and toxicity assessments (subacute, anaphylactic shock, persistence, virulence).
- Tests were conducted on mice, guinea pigs, rabbits, and goldfish at doses significantly higher than those effective against mosquito larvae.
- Ocular irritation and skin scarification tests were performed on rabbits.
Main Results:
- No mortality or abnormal reactions were observed in mammals, even at doses 1,000 times higher than World Health Organization (WHO) safety levels.
- Bacterial cells showed no toxicity in goldfish at doses 1,000 times higher than the LD50 for mosquito larvae.
- No adverse effects were noted during subacute toxicity, anaphylactic shock, persistence, or virulence tests.
Conclusions:
- Clostridium bifermentans serovar malaysia bacterial cells are safe for laboratory mammals.
- The bacterium poses no toxic risk to goldfish, even at elevated concentrations.
- These findings support the potential use of C. bifermentans serovar malaysia as a safe and effective mosquito control agent.