In this article the author focuses on the association of plant sap with nutrient-providing bacterial endosymbionts involving a nested symbiosis in which the Planococcus citri betaproteobacterial endosymbiont harbours the gammaproteobacterium Candidatus Moranella endobia. It states that the essential metabolic pathways in this symbiotic mosaic are completed by heterologous complementation from an extraordinary variety of sources