Comparative Analysis of Gut Eukaryotic Communities in Three Laboratory-Reared Cockroach Species Using Metabarcoding.

Cockroaches are known reservoirs for diverse bacterial microbiomes. However, comprehensive analyses of the eukaryotic communities within cockroaches remain limited. In this study, we selected three long-term laboratory-reared cockroach species (Blattella germanica, Periplaneta fuliginosa, and Periplaneta japonica) and performed metabarcoding of the 18S rRNA V9 region using the iSeq 100 platform. The nematode Blatticola blattae was identified in B. germanica, and Leidynema appendiculata was found in both P. fuliginosa and P. japonica. The amplicon sequence variant (ASV) of Nyctotherus (Ciliophora) was detected in all three species of cockroach, while Entamoeba sp. was detected in P. fuliginosa and P. japonica. Compared with the other two species, B. germanica exhibited a higher prevalence of the fungus Nephridiophaga. Our findings showed that laboratory-reared cockroaches belonging to different species harbored distinct commensal and parasitic eukaryotic taxa. While most ASVs were of reduced clinical concern for humans as opposed to studies using wild-caught specimens, the detection of commensals, arthropod parasites and potential human pathogens illustrates the complexity of the cockroach-associated eukaryome and the influence of host identity. Our study emphasizes the importance of host-specificity in the eukaryotic community of laboratory-reared cockroach models.