Microbial biocontrol agents are promising tools to reduce the use of chemical pesticides in agriculture. They represent one of the few means of intervention in organic farming, which makes the success of their use particularly important. Due to their special characteristics (living organisms), their deployment is more complex than applying chemical molecules. This can hinder their adoption and foster the variability of their efficacy. Taking this complexity into account would make their use more reliable. This complexity is difficult to envisage in simple product data sheets. Thus, to facilitate advice to farmers, it is necessary to develop decision support systems, integrating the biological properties of biocontrol agents, those of plant pathogens, and the characteristics of cropping systems. Therefore, our first objective is to identify and prioritize the factors governing the efficacy of microbial biocontrol agents. To this end, the conduction of surveys of farmers, advisers and producers of biocontrol agents and a meta-analysis of scientific and technical literature is currently underway. Preliminary results of this analysis will be presented during this talk.