THE COMPLEX AND MULTIFORM RELATIONSHIP BETWEEN NEMATODA AND BACTERIA

The relationship between nematodes and bacteria has taken place in different ways, from the simple trophicrelation to the most sophisticated forms of symbiosis. Such symbiosis is not a primitive condition but it appeared and wasestablished, being advantageous, during the evolution of different nematode taxa, independently and with different,sometimes complex, modalities ranging from mutualism to parasitism. The most significant modalities of mutualism areexposed here with particular stress on the highly specific relationship between entomopathogenic nematodes of thefamilies Heterorhabditidae and Steinernematidae and their symbionts. This relationship, fruit of co-evolution betweenthe nematodes and their bacteria, is treated from different points of view and at the light of the most recent geneticresearch.