Honeybee holobiont responses to environmental perturbations, especially to invasive bioagressors – holoBEEont

The honeybee Apis mellifera is an emblematic species of ecosystemic and economical importance that has experienced massive colony losses worldwide. The HOLOBEEONT project aims at improving our understanding of honeybee responses to their abiotic environment and to bioagressors, from a holobiont perspective, i.e. considering bee hosts along with their cohorts of the microbial symbionts as distinct functional and evolutionary units. Here we consider two honeybee subspecies: A. mellifera unicolor (African A lineage) and A. m. mellifera (European M lineage). For each subspecies we have the opportunity to follow the evolution of the holobiont in islands recently disturbed by the introduction of invasive honeybee bioagressors. On the tropical island of Reunion (Indian Ocean), A. m. unicolor faces the introduction of the mite Varroa destructor in 2017, then of the small hive beetle Aethina tumida in 2022. The temperate island of Ouessant (Ushant) was invaded by V. destructor in 2021. The project is a collaborative effort involving five partners with critical expertise in honeybee genetics, microbiota monitoring, epidemiological surveillance, insular ecology and population genomics.
In the first work package, we will explore how abiotic environmental conditions impact the diversity and structure of the honeybee gut microbiota in the South West Indian Ocean. In the second work package, we will describe the impact of invasive bioagressors on honeybee holobionts by sequencing both the hosts' and microbiota genomes to identify potential host/symbionts co-adaptations. In the third work package, we ask whether invasive bioagressors may disrupt the honeybee pathosphere by following the dynamics of pathogens in La Réunion and comparing the virulence of introduced Deformed Wing Virus (DWV) strains between subspecies. The HOLOBEEONT project will shed a new light on how the honeybee holobiont responds to both biotic and abiotic disturbances by producing new, original data that are crucial for improving honeybee conservation and management in a changing environment.