Introduction Approximately 1 million species of insects in 25 orders and more than 600 families have been described. It is estimated that as many as 30 million species may exist. In light of this diversity, it is difficult to summarize the immunology of even a portion of the insects in a single paper. This review will illustrate examples from selected insect species to give a flavour of insect immunology as a whole. Because of their short life spans relative to most mammals and the diversity of their habitats, insects face unique immunological challenges.
Insects also serve as vectors for human diseases such as malaria and trypanosomiasis.
Knowledge of the insect immune system can therefore yield information important in the prevention of human disease and the study of immunology in general. The study of insect immunology may demonstrate alternative antimicrobial strategies compared with our current paradigms. A better knowledge of insect immunology can improve both our basic and applied sciences in several areas. In vertebrates, acquired immunity can take days or weeks to develop. To test for immunological memory, cockroaches were immunized with heat killed Pseudomonas aeruginosa , rested, and challenged with an LD 100 dose of living P. aeruginosa .