# Stage-Specific Microbiota Transitions Throughout Black Soldier Fly Ontogeny

## TL;DR

This study explores how the black soldier fly's microbiota changes during its life stages, focusing on the transition from larvae to eggs and its impact on oviposition.

## Contribution

The study identifies stage-specific microbiota transitions, particularly the shift from Enterobacteriaceae to Burkholderiaceae, and their role in oviposition behavior.

## Key findings

- Larval stages are dominated by Morganella, Escherichia, and Proteus, while egg samples show dominance of Burkholderia-Caballeronia-Paraburkholderia.
- Microbial community composition transforms progressively during maturation, especially before oviposition.
- Understanding egg surface microbiota can improve egg production and mass harvesting of BSF larvae.

## Abstract

The growing global population increases the demand for protein, while organic waste management has become more challenging. Alternative protein sources are essential to mitigate the environmental impact of food production. The black soldier fly (BSF; Hermetia illucens) has emerged as an alternative to traditional protein sources (e.g., soybean meal, fishmeal) due to its ability to convert diverse organic waste, addressing both issues simultaneously. This makes the BSF a promising candidate for industrial rearing, with its successful development closely tied to microbial influences on growth and behaviour, particularly bacterial influences on oviposition. In this study, we focus on the microbiota throughout insect development with a special focus on egg surface microbiota and their origin. We analysed the microbiota in the haemolymph and gut of larvae raised on sterilized and non-sterilized feed, pupal cell pulp, the wash of the ovipositor, eggs directly collected after oviposition, ovarian eggs, the empty female abdomen, eggs exposed to adult BSF, and surface-sterilized eggs. Our analysis revealed distinct bacterial community profiles across life stages, indicating a transition from larval dominance of Enterobacteriaceae to Burkholderiaceae on all analysed eggs. At the genus level, larval stages were characterized by Morganella, Escherichia, and Proteus, transitioning to less diverse communities in egg samples predominated by Burkholderia-Caballeronia-Paraburkholderia. Our study reveals that while predominant microbiota persist throughout all life stages, microbial community composition transforms progressively during maturation, particularly before oviposition. Understanding egg surface microbiota and the cues guiding oviposition has the potential to boost egg production and simplify mass harvesting of BSF larvae.

The online version contains supplementary material available at 10.1007/s00248-025-02691-1.