German cockroaches (Blattella germanica) and bed bugs (Cimex lectularius) are common indoor pests, especially in low-income communities. Infestations of these pests might range from a few insects to thousands of individuals in a single dwelling. Besides being nuisance pests, the presence of these insects causes severe distress and adverse health effects in infested residences. These two insect species have different biology, feeding habits and they occupy different niches within homes. German cockroaches are omnivorous and associate mainly with kitchens, whereas bed bugs are obligatory hematophagous insects found mainly in bedrooms. Thus, these two species inhabit environments with different microbial communities. However, the impacts of the environment on the gut microbiomes of these insects, and the impacts of the gut microbiomes on the microbial communities of homes have not been investigated. We characterized the microbial diversity of different populations of field-collected German cockroaches and bed bugs along with insects from lab colonies. Simultaneously, we also characterized the indoor dust microbiome of the respective homes. Insect and dust samples were analyzed by high-throughput sequencing of the variable V3-V4 region of bacterial 16S rRNA gene on the Illumina Mi-Seq platform. The total microbial abundance was quantified by qPCR.
Results/Conclusions
Our results indicate that cockroaches harbor a diverse array of bacteria in their gut. Lab-reared and field-collected cockroaches have distinct microbial community composition, but all samples shared some core bacterial taxa, suggesting common underlying functional roles of these taxa. Blattabacterium, an obligatory endosymbiont of cockroaches was found in all the samples, but its abundance varied significantly among samples. Being a nutritional endosymbiont, the underlying reasons for the variations of this bacterium among samples is under investigation. Unlike German cockroaches, the bed bug microbiome is comprised predominantly of two obligatory endosymbionts: Wolbachia and an unclassified member of Enterobacteriaceae. We found no significant differences in the microbial composition among various bed bug populations. DNA of dust samples from bed bug infested homes showed a strong influence of bed bugs on the microbial diversity of indoor settled dust. While there is a correlation between pest infestation and dust-associated microbes, further studies are warranted to understand the fate of these communities in the indoor environment and the potential risk they might pose to human health.