Assessing the impact of diet formulation and age on targeted bacterial establishment in laboratory and mass-reared Mediterranean fruit fly using full-length 16S rRNA sequencing.

Insect gut microbiota play important roles in host health and interactions with the environment. In laboratory and mass-reared insects, gut microbiomes can differ in composition and function compared to wild conspecifics. For fruit flies, such as the Mediterranean fruit fly (medfly; IMPORTANCE: Insects form intimate relationships with gut microorganisms that can help facilitate several important roles. The goal of our study was to evaluate factors that influence microbial establishment in lines of the Mediterranean fruit fly (medfly), an important pest species worldwide. Mass-reared insects for the sterile insect technique often possess gut microbiomes that substantially differ from wild flies, which can impact their performance in pest control contexts. Here, we show that liquid-based formulations can be utilized to manipulate the gut microbiota of mass-reared medflies. Furthermore, using near full-length 16S rRNA metabarcoding sequencing, we uncovered strain-level diversity that was not immediately obvious using other approaches. This is a notable finding, as it suggests that full-length 16S rRNA approaches can have marked improvements for some taxa compared to fewer hypervariable regions at approximately the same cost. Our results provide new avenues for exploring and interrogating medfly-microbiome interactions.