Bacterial symbionts and their hosts have developed diverse mechanisms that not only facilitate recognition of each other, but also play a key role in symbiont proliferation in tissues and cells of their eukaryote hosts. We consider the tripartite symbiotic interaction represented by entomopathogenic nematodes, their bacterial symbionts and insect hosts to investigate the high level of integration and specialization these organisms have with each other and have developed to access an insect host.  Specifically, we are currently studying recognition and colonization of host tissues by entomopathogenic bacteria in both its mutualistic and pathogenic phase considering a multidisciplinary approach including histology and biochemistry coupled with a lipidomic/proteomic and genomic tools.