Related Experiment Video

Updated: Jun 10, 2026

Protocols for Testing the Toxicity of Novel Insecticidal Chemistries to Mosquitoes
09:32

Protocols for Testing the Toxicity of Novel Insecticidal Chemistries to Mosquitoes

Published on: February 13, 2019

Characterization of highly toxic indigenous strains of mosquitocidal organism Bacillus sphaericus

Ramesh S Hire1, Ashok B Hadapad, Narayanan Vijayalakshmi

  • 1Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre (BARC), Trombay, Mumbai, India.

FEMS Microbiology Letters
|July 28, 2010
PubMed

Insights

Bacillus sphaericus isolate ISPC-8 shows high spore viability and potent mosquitocidal activity against Culex quinquefasciatus. This promising biopesticide candidate possesses binary toxin genes with unique protein variations.

Area of Science:

  • Microbiology
  • Entomology
  • Biotechnology

Background:

  • Bacillus sphaericus is a bacterium known for its mosquitocidal properties.
  • Developing effective biopesticides is crucial for integrated vector management.
  • Indigenous isolates offer potential for novel and potent biopesticidal agents.

Purpose of the Study:

  • To evaluate indigenous Bacillus sphaericus isolates for spore viability and mosquitocidal efficacy.
  • To identify potent isolates for biopesticide development.
  • To characterize the binary toxin genes and proteins of the most promising isolate.

Main Methods:

  • Comparative analysis of spore viability and total viability count (TVC) for indigenous and standard Bacillus sphaericus strains.
  • Determination of lethal concentration 50 (LC50) values against mosquito larvae (Culex quinquefasciatus).
  • Host spectrum analysis against various mosquito species.
  • Detection and comparative sequence analysis of binary toxin genes (binA and binB).
  • Purification and bioassay of binary proteins.

Main Results:

  • Bacillus sphaericus isolate ISPC-8 demonstrated significantly higher TVC (1.3 x 10^9 spores mL^-1) and lower LC50 values (0.68 x 10^3 spores mL^-1) against Culex quinquefasciatus compared to standard strains.
  • ISPC-8 exhibited broad host spectrum activity, with highest efficacy against C. quinquefasciatus, followed by Culex tritaeniorhynchus, Aedes albopictus, and Aedes aegypti.
  • Only ISPC-8 possessed binary toxin genes (binA and binB), with unique amino acid variations in its BinA and BinB proteins compared to standard strains.
  • Purified binary proteins from ISPC-8 showed potent larvicidal activity with an LC50 of 6.32 ng mL^-1 against C. quinquefasciatus.

Conclusions:

  • Indigenous Bacillus sphaericus isolate ISPC-8 is a highly viable and virulent strain with significant mosquitocidal potential.
  • ISPC-8 represents a promising candidate for developing novel biopesticides, particularly against Culex species.
  • The unique genetic and protein characteristics of ISPC-8's binary toxins may contribute to its enhanced efficacy.

More Related Videos

The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis13:00

The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis

Published on: December 11, 2012

Topical Application Bioassay to Quantify Insecticide Toxicity for Mosquitoes and Fruit Flies09:37

Topical Application Bioassay to Quantify Insecticide Toxicity for Mosquitoes and Fruit Flies

Published on: January 19, 2022

Related Concept Videos

Inhalation Anthrax01:25

Inhalation Anthrax

Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive, spore-forming bacterium. It primarily affects herbivorous animals but can be transmitted to humans through skin contact, ingestion, or inhalation of spores.Cutaneous anthrax, the most common form, typically results from direct contact with bacterial spores through skin abrasions and is generally less severe. Gastrointestinal anthrax results from eating undercooked or contaminated meat. It affects the mouth, throat, or...
Production of Biopesticides01:18

Production of Biopesticides

Biopesticides offer a sustainable alternative to chemical pesticides, utilizing microbial agents to control agricultural pests. Bacillus thuringiensis (Bt) is a widely employed bacterium known for its potent insecticidal activity. Bt biopesticides are favored for their specificity to insect pests, minimal environmental impact, and natural degradability.Mechanism of Bt Toxin Action Bt produces insecticidal crystal (Cry) proteins during its sporulation phase. These proteins form parasporal...
Bacterial Toxins01:12

Bacterial Toxins

Bacterial toxins are sophisticated virulence factors that enable pathogenic bacteria to interact with, invade, and damage host tissues. These toxins fall broadly into two types: protein exotoxins, which are secreted into the environment and target specific host receptors, and lipopolysaccharide endotoxins, which are structural components of the bacterial outer membrane released primarily during bacterial lysis or membrane shedding. Exotoxins generally act more selectively, binding to cell...
Clinical Significance of Antibiotic Resistance01:25

Clinical Significance of Antibiotic Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Defense Against Bacterial Pathogens01:31

Defense Against Bacterial Pathogens

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...