Bacterial Pathogens

Bacteria are small unicellullar prokaryotes (do not have a defined nucleus). They have rigid cell walls and generally range from under 1µ to over 5µ in length. Bacterial species are extremely variable. Some species produce cells that occur singularly while others occur in chains or packets. Reproduction is usually by binary fission, but a sexual component is present in the reproductive process of some species. Some species are motile while others are nonmotile. Some require oxygen, while others develop best in an anaerobic environment. The specific identification of a bacterial isolate is often difficult and usually requires the input of a bacterial taxonomist.

Bacterial pathogens of insects can be divided into two broad categories, non-spore-forming bacteria and spore-forming bacteria. Although most of the species of bacteria isolated from diseased insects are non-spore-forming bacteria, spore-forming bacteria in the genus Bacillus are the most important from the standpoint of biological control.