[en] The economic losses caused by post-harvest pathogens of apple and pear can still reach 25 %. There is currently an increasing demand to develop sustainable methods to control these post-harvest pathogens. Biocontrol agents are interesting candidates to answer this demand. Nevertheless, their commercial development is sometimes hampered by a low or non-reliable efficacy comparing to fungicide treatments. Fundamental research on the mode of action of the BCA and of its ecological fitness could help to overcome that phenomenon. This chapter reviews the progresses made during two decades to understand the mode of action and the ecological niche of two BCA, Pichia anomala strain K and Candida oleophila strain O. These advances required the combination of various methodologies (in vitro and in situ) and techniques (microbiology, microscopy, genome characterization, transcriptome, proteome, gene disruption. . .) which are summarized here. Importantly, the practical impact of these discoveries to improve the efficacy of the biopesticide is also highlighted.
