Of Cockroaches and Symbionts: Recent Advances in the Characterization of the Relationship between Blattella germanica and Its Dual Symbiotic System

Abstract

Mutualistic stable symbioses are widespread in all groups of eukaryotes, especially in insects, where symbionts have played an essential role in their evolution. Many insects live in obligate relationship with different ecto- and endosymbiotic bacteria, which are needed to maintain their hosts’ fitness in their natural environment, to the point of even relying on them for survival. The case of cockroaches (Blattodea) is paradigmatic, as both symbiotic systems coexist in the same organism in two separated compartments: an intracellular endosymbiont (Blattabacterium) inside bacteriocytes located in the fat body, and a rich and complex microbiota in the hindgut. The German cockroach Blattella germanica is a good model for the study of symbiotic interactions, as it can be maintained in the laboratory in controlled populations, allowing the perturbations of the two symbiotic systems in order to study the communication and integration of the tripartite organization of the host–endosymbiont–microbiota, and to evaluate the role of symbiotic antimicrobial peptides (AMPs) in host control over their symbionts. The importance of cockroaches as reservoirs and transmission vectors of antibiotic resistance sequences, and their putative interest to search for AMPs to deal with the problem, is also discussed.

Variable organization of symbiont-containing tissue across planthoppers hosting different heritable endosymbionts

“…We showed that in planthoppers, like in beetles, cockroaches, and other hemipterans, bacteriocytes/bacteriomes are usually distributed in the body cavity within fat body tissue, usually close to reproductive organs or intestine ( Buchner, 1965 ; Michalik et al, 2014a ; Michalik et al, 2014b ; Michalik et al, 2018a ; Michalik et al, 2018b ; Hirota et al, 2020 ; Latorre et al, 2022 ). In contrast, in Camponotus ants, Hippoboscoidea flies, and some sucking lice, bacteriocytes are directly associated with the intestinal wall.…”

“…Monosymbiotic bacteriomes, bearing a single symbiont taxon and with relatively simple organization, are common in insects (Buchner, 1965). Some of the better-known examples include cockroaches (Blattobacterium), tsetse flies (Wigglesworthia), aphids (Buchnera), and scale insects (Tremblaya phenacola, Kotejella) (Rio et al, 2012;Michalik et al, 2014b;Michalik et al, 2018b;Michalik et al, 2019;Latorre et al, 2022). The less common are disymbiotic bacteriomes harboring two different types of microorganisms.…”

Comparative Transcriptomics of Fat Bodies between Symbiotic and Quasi-Aposymbiotic Adult Females of Blattella germanica with Emphasis on the Metabolic Integration with Its Endosymbiont Blattabacterium and Its Immune System

“…The German cockroach Blattella germanica (Blattodea) is a good model to study these complex symbiotic relationships because two symbiotic systems coexist in a single individual: a bacterial obligate intracellular endosymbiont Blattabacterium cuenoti (hereinafter Blattabacterium) [14] and a rich and complex gut microbiota [15]. Blattabacterium, a Gramnegative bacterium belonging to the phylum Bacteroidetes, is vertically transmitted from mother to offspring through the infection of the oocytes in each generation [16][17][18].…”

Wolbachia infection in native populations of Blattella germanica and Periplaneta americana

“…In recent years, many studies have shown that cockroaches are rich in microbes [ 3 , 4 , 16 , 18 ], and some of these microbes have formed an interdependent symbiotic relationship with the host during the long-term co-evolution process. Wolbachia is a gram-negative, maternally inherited, intracellular Rickettsia-like alphaproteobacterium that is found in many arthropods, such as insects, mites, ticks, arachnids, terrestrial crustaceans (Isopods) and filarial nematodes [ 19 ].…”