ENTOMOLOGY 135

INTRODUCTION TO BIOLOGICAL CONTROL

Biology of Bacterial Pathogens

See Handout: Introduction to Insect Pathology

I. Bacterial Pathogens of Insects

1. Sporeformers
   1. Bacillus
   2. Clostridium
2. Nonsporeformers
   1. Pseudomonas
   2. Streptococcus
   3. Serratia
   4. Xenorhabdus and Photorhabdus (covered in more detail with nematodes)

II. Bacillus sphaericus (facultative pathogen)

1. Brief introduction - used for mosquito control in polluted water
2. Host range (Culex, then Anopheles, then Aedes)

III. Bacillus thuringiensis (Bt) (facultative pathogen)

1. Spore morphology
2. Bt subspecies (thuringiensis and kurstaki)
3. delta endotoxin - cry I, cry II, cry III, cry IV
   1. cryI - Lepidoptera-specific
   2. cryII - Lepidoptera- and Diptera-specific
   3. cryIII - Coleoptera-specific
   4. cryIV - Diptera-specific
4. beta exotoxin (thuringiensin)
5. Host range
6. Mode of infection
7. Period of lethal infection
8. Resistance in insects

IV. Bacillus thuringiensis subsp. israelensis (Bti)

1. Host range (Culex and Aedes, less susceptible Anopheles)
2. Period of lethal infection

V. Bacillus thuringiensis subsp. tenebrionis (also formerly as subsp. san diego)

1. Host range (Colorado potato beetle and elm leaf leaf beetle)
2. Period of lethal infection

VI. Bacillus popilliae and B. lentimorbus (to be covered in detail later)

Selected References

• Burges, H. D. (ed).1981. Microbial control of pests and plant diseases 1970-1980. Academic Press. New York. Chap 10 and 11.
• de Barjac, H. and Sutherland, D. J.1990. Bacterial Control of Mosquitoes and Black Flies. Rutgers University Press, New Brunswick. 349 pp
• Gill, S. S., Cowles, E. A. and Pietrantonio, P. V.1992. The mode of action of Bacillus thuringiensis endotoxins. Annu. Rev. Entomol. 37:615-636.
• Hofte, H. and Whitely, H. R.1989. Insecticidal crystal proteins of Bacillus thuringiensis. Microbiol. Rev. 53: 242-255.
• Tabashnik, B. E.1994. Evolution of resistance to Bacillus thuringiensis. Annu Rev. Entomol. 39: 47-79.
• Tanada, Y. and Kaya, H. K.1993. Insect Pathology. Academic Press, San Diego. Chapter 4. pages 83-112.

* Bt toxic to ants and nematodes have also been found. The gene and protein have not been assigned to a specific group.

+ "cry" is the Bt gene that produces the protein designated as "Cry." The principal host spectrum is designated by the addition of a Roman numeral. Thus, CryI and CryII refers to proteins that are specific to Lepidoptera (larvae of moths and butterflies) and Diptera/Lepidoptera (larvae of mosquitoes/moths and butterflies), respectively. The gene or protein can be further differentiated by capital letters (cryIA or CryIA) that indicate major differences in amino acid sequences (as well as the chronological order in which a gene sequence was published). Minor differences are designated by lower case letters in parentheses, that is cryIA(a) or CryIA(a).

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