Intracellular Symbiotic Bacteria Within Insects

Symbiosis is a permanent and hereditary association between two or more partners specifically distinct and, most of the time, very different from a phylogenetic point of view. A very common type of symbiosis involves bacteria, called endocytobiotes, living inside eukaryotic cells. Our investigation was limited to the endocytobiotes of insects. Most of the time they are Gram negative and non sporulating bacteria (Dash et al., 1989). Such a habitat is very particular or extreme for at least three reasons: first, the bacteria, associated with their host, constitute a new biological unit, the symbiocosm, which is submitted to natural selection (Nardon and Grenier, 1993). Second, in this symbiocosm, the bacteria entirely depend on the host for their nutrition, and third, the growth of bacteria is strictly controlled by the insect (Nardon et al., 1998).