Mosquitoes and black flies are a constant threat to health and comfort, yet the modern chemical pesticides used to control them have cre ated serious ecological problems. Populations of resistant mosquitoes and black flies have evolved, beneficial insects and natural predators have been destroyed, and environmental pollution has increased worldwide. Therefore, scientists have energetically sought new, environmentally safe technologies to combat mosquitoes and black flies and the diseases they carry. Among the most effective alternative means of controlling these pests are the highly spe cific microbial agents derived from Bacillus tburingiensis or Bacillus spbaericus. The microbial control of mosquitoes and black flies is a very important, rapidly developing area of science. Entomologists and microbiologists have already achieved spectacular successes using B. tburingiensis and B. spbaericus against these pests. Recent discoveries of new bacterial isolates specific to new hosts and recent genetic improvements in these isolates have created the potential for wide-scale use of these biological control agents. Efficient microbial control of mosquitoes and black flies can now be achieved, but a proper knowledge of factors relating to the safe and effective use of these biological control agents is necessary. The efficacy of B. tburingiensis and B. spbaericus is influenced by the inherent differential tol erance of the target mosquitoes or black flies, by the formulation technology and application of these agents, and by environmental factors, especially sun light and temperature.

Inhaltsangabe1 Bacillus thuringiensis subsp. israelensis (B.t.i.).- 1 Discovery of Bacillus thuringiensis israelensis.- 1.1 Introduction.- 1.2 Geography, Climate, and Environmental Conditions.- 1.3 Detection and Isolation.- 2 Characterization and Prospective View of Bacillus thuringiensis israelensis.- 3 Parasporal Body of Bacillus thuringiensis israelensis: Structure, Protein Composition, and Toxicity.- 3.1 Introduction.- 3.2 Synthesis.- 3.3 Structure.- 3.4 Purification and Solubilization.- 3.5 Protein Composition.- 3.6 Toxicity.- 3.6.1 Intact or Solubilized Parasporal Body.- 3.6.2 The 27-kDa Protein.- 3.6.3 The 65-kDa Protein.- 3.6.4 The 128- and 135-kDa Proteins.- 3.6.5 Synergistic Interaction of Toxic Proteins.- 3.7 Mosquiticidal Parasporal Bodies of Other Subspecies of B. thuringiensis.- 3.8 Discussion.- 4 Mechanism of Action of Bacillus thuringiensis israelensis Parasporal Body.- 4.1 Introduction.- 4.2 Mechanism of Action.- 4.2.1 Receptors.- 4.2.2 Toxin Structure and Membrane Insertion.- 4.2.3 Colloid-Osmotic Lysis Theory.- 4.2.4 Toxin Oligomerization.- 4.3 Discussion.- 5 Genetics of Bacillus thuringiensis israelensis.- 5.1 Introduction.- 5.2 Genetic Exchange Systems.- 5.2.1 Transformation.- 5.2.2 Transduction.- 5.2.3 Plasmid Transfer.- 5.3 Plasmids and Crystal Toxin Production.- 5.3.1 Plasmids and Plasmid Curing Analysis.- 5.3.2 Location of the ?-endotoxin Gene.- 5.4 Cloning of the Crystal Toxin Gene(s).- 5.5 Genetics and Biochemistry of the Crystal Toxin.- 5.6 Conclusions.- 6 Cloning of Bacillus thuringiensis israelensis Mosquito Toxin Genes.- 6.1 Introduction.- 6.2 Early Confusion in Cloning B.t.i. Toxin Protein Genes.- 6.3 Current Picture of B.t.i. Toxin Protein Genes.- 6.4 Discussion.- 7 Transfer of the Bacillus thuringiensis israelensis Mosquiticidal Toxin Gene into Mosquito Larval Food Sources.- 7.1 Introduction.- 7.2 Assignment of Toxic Activity.- 7.3 Cloning of the Mosquito Toxin Gene.- 7.4 Mosquito and Black Fly Larval Food Sources.- 7.5 Introduction of the Mosquito Toxin Gene into Larval Food Sources.- 7.6 Safety Aspects.- 8 Potential for Improved Formulations of Bacillus thuringiensis israelensis through Standardization and Fermentation Development.- 8.1 Introduction.- 8.2 History.- 8.2.1 Background.- 8.2.2 Discovery and Early History.- 8.2.3 Standardizing and Measuring B.t. Products.- 8.2.3.1 Early Concepts.- 8.2.3.2 The Spore Count.- 8.3 Bioassays and the International Unit.- 8.3.1 Philosophical Differences between Bioassays of Chemical and Microbial Insecticides.- 8.3.2 Bioassays and the LC50.- 8.3.3 Choice of Insect Species for Bioassay.- 8.3.4 The International Unit.- 8.3.5 The de Barjac Protocol for B.t.i.: Its Design and Principles.- 8.3.5.1 Preparation of Stock Suspension of the Standard.- 8.3.5.2 Preparation of Suspension of the Test Samples.- 8.3.5.3 Specifications for Larvae Used in Assay.- 8.3.5.4 Reading the Assay.- 8.3.5.5 Evaluations of Assays and Their Reproducibility.- 8.4 Activity Ratios.- 8.4.1 Definition of Activity Ratios.- 8.4.2 Use and Significance of Activity Ratios.- 8.4.2.1 Tn/Hv Ratios of subspecies kurstaki.- 8.4.2.2 Cq/Aa Ratios of subspecies israelensis.- 8.4.2.3 Reproducibility of Activity Ratios in Fermentation Studies.- 8.5 Potential for Improvements in Production of the B.t.i. Toxin.- 8.5.1 Fermentation.- 8.5.1.1 Strain Selection.- 8.5.1.2 Aeration.- 8.5.1.3 Selection of Nutrients.- 8.5.2 Recovery.- 8.5.2.1 Spore-crystal Formulations.- 8.5.2.2 Viable Spore-free Formulations.- 8.6 Summary.- 8.6.1 Bioassays and the Production of B.t.- 8.6.2 Bioassays and the Future of B.t.- 9 Activity, Field Efficacy, and Use of Bacillus thuringiensis israelensis against Mosquitoes.- 9.1 Introduction.- 9.2 Laboratory Evaluation.- 9.2.1 Screening Procedures.- 9.2.2 Preliminary Screening.- 9.2.3 Species Specificity.- 9.2.4 Instar Susceptibility.- 9.2.5 Biotic and Abiotic Factors Influencing Activity.- 9.2.6 Delayed Effects.- 9.3 Field Evaluation and Efficacy Trials.- 9.3.1 Spectrum of Field Activity.- 9 3.1