Explaining and predicting natural variation in infection outcomes continues to be a pressing issue in disease research, and recent evidence from several systems suggests that variation in microbiome community composition and stability can contribute to this inter-individual heterogeneity. The red flour beetle, Tribolium castaneum, has emerged as an excellent model system to connect natural variation in host-microbe dynamics with epidemiological dynamics because it is easy to collect in the wild, simple to maintain in the laboratory, and has a suite of functional genetics tools available for manipulation of host physiological processes. However, despite hints that alteration of the gut microbiota qualitatively shifts disease susceptibility in this system, the T. castaneum gut microbiome has yet to be characterized. This study describes the bacterial and fungal gut microbiome of T. castaneum using 16s sequencing and fluorescence in situ hybridization (FISH).
Results/Conclusions
16s sequencing and FISH imaging results reveal no resident bacteria in lab reared larvae and adult beetles, whereas ITS sequencing shows multiple fungal species residing within the beetle gut that remain stable even when the gut is colonized by a bacterial symbiont. Our results suggest that the lack of bacteria in the microbiome might be at least partially density-dependent, driven by the accumulation of antimicrobial quinones secreted by the beetles in the food medium. These results encourage future studies on the impact of fungal microbiota communities on bacterial colonization, host immunity, and disease heterogeneity, as well as interactions among host population dynamics and gut microbiota.