Bacterial association observations in Lucilia sericata and Lucilia cuprina organs through 16S rRNA gene sequencing

Blowfly (Diptera: Calliphoridae) species Lucilia sericata (Meigen) and related species Lucilia cuprina (Wiedmann) are important agricultural pests, assist in forensic fields and also have a therapeutic role in medicine. Both species (though predominantly L. sericata) are utilised in a clinical setting for maggot debridement therapy (MDT) where the larvae ingest necrotic tissue and bacteria from non-healing wounds. Conversely, larvae of L. cuprina feed invasively, as major initiators of sheep myiasis in Australia, New Zealand, and the UK, among other regions. Both species exhibit larval and adult interactions with bacterially rich environments, but the significance of this in the composition of their microbiome has yet to be considered. This study utilised dissected samples of digestive and reproductive organs from both disinfected and non-disinfected adults and larvae of both species for bacterial DNA extraction, followed by 16S rRNA gene sequencing. Sequencing data indicated unsurprisingly that digestive tracts of both genders and female salivary glands from all non-disinfected samples carry the most concentrated amounts of bacteria. Genera Pseudomonas and Corynebacterium were also highly represented within all organs and species analysed. Comparison of bait lures to sample sequence read output of insect specimens showed no correlation with genera such as Pseudomonas present in insects, while absent from wild bait, and in reduced amounts from fleece bait profiles. With this information, future work can focus on key organs such as the spermathecae and salivary glands, while also providing the potential to identify the role these bacteria may play in the blowfly life cycle. KEY POINTS: Genera Pseudomonas appears consistently in the microbiome of Lucilia species. Female spermathecae and salivary glands show the highest microbial diversity. Bacterial profiles of L. sericata and L. cuprina have similar composition.