Mosquito-microbiota interactions shape the structure and stability of carnivorous pitcher plant communities

The leaves of carnivorous purple pitcher plants (Sarracenia purpurea) harbor diverse communities of inquiline species, including bacteria and larvae of the pitcher plant mosquito (Wyeomyia smithii), which aid the plant by processing captured prey. Despite the growing appreciation for this microecosystem as a tractable model in which to study food web dynamics and the moniker of W. smithii as a ‘keystone predator’, very little is known about microbiota acquisition and assembly in W. smithii mosquitoes or the impacts of W. smithii-microbiota interactions on mosquito and/or plant fitness. Here, we present results from high-throughput 16S rRNA gene amplicon sequencing studies that support a dominant role for the pitcher environment in shaping microbiota diversity in W. smithii larvae and indicate that pitcher-associated microbiota can persist in and be dispersed by adult W. smithii mosquitoes. We also demonstrate the successful generation of axenic W. smithii larvae and report variable fitness outcomes in gnotobiotic larvae monocolonized by individual bacterial isolates derived from naturally occurring pitchers in the field. Results from a longitudinal field experiment to quantify the impacts of mosquito enrichment or depletion on pitcher-associated microbiota assembly and plant fitness are also discussed. Altogether, these results lay the foundation for future studies to understand the mechanisms underlying how W. smithii-microbiota interactions shape the structure and stability of this important model ecosystem.