Protozoans ("first animals") are
single-celled heterotrophic organisms that are members of
the Kingdom Protista.
Protists are a diverse group of creatures that may have
characteristics of animals or plants or both. Of the 40,000
known protist species, approximately 15,000 are protozoans.
However, there are roughly 1200 protozoan species that are
specific to and causing diseases in insects. One group, the
Microsporidia
(shown at right), have shown promise as biological control
agents of insects. The Microsporidia are slow acting and may
need several days or weeks to harm the insect. Instead of
killing the insect these protozoans reduce host reproduction
or feeding. Microsporidia infect a wide range of insects,
but the technology is relatively new and it will take some
time to perfect the use of these organisms.
