Study of the interaction among microorganisms, plants and honeybees for the benefit of environmental health and sustainability

Nowadays, the ongoing climate change together with the strong anthropogenic modifications at landscape level have led to drastic ecosystem and agroecosystem alterations, that are impacting on biological processes necessary to maintain the ecosystem balance. In this context, the scientific community agrees in the importance of the microbial communities each ecological niche, whose degradation can lead to dramatic consequences. The presented thesis aims to achieve scientific advancements in the understanding of complex microbial interactions and contribution in the soil- plants-pollinators network in the agroecosystem. In particular, the main focus reported are addressing how the anthropogenic activities impact the pollinators microbiota; the microorganisms as an ecofriendly tool to counteract honeybees pathogens; and finally, how the microorganism affect sunflower-pollinators ecosphere. In particular, the effect of exogenous microbial strains (with PGPB activity) on sunflower rhizosphere endophytic community and volatile organic compounds (VOCs) were evaluated. The obtained results showed that anthropogenic activities can impact the pollinators microbiome leading to dysbiosis and pathogens proliferation, however, ecofriendly solutions such as beneficial bacteria can control pathogens without disturbing their core microbiome. Moreover, the anthropogenic activities can interfere in the availability of trophic sources for pollinators. However, results show that a responsible management of the soil microbial communities of the sunflower rhizosphere, through ecological fertilizers, can enhance the VOCs profile, increasing the attractivity to pollinators. Not only this, but the use of ecological fertilizers can also improve the gene expression of sugar transporters involved in nectar secretion. These results propose a holistic approach that can be used for a deeper understanding of the complex ecosystemic interaction between soil- plants-pollinators network, in connection with the human activities.