Discovering Ecological Interactions Between Biocontrol Bacterial Strains and Entomopathogenic Nematodes in Button...

The substrate for button mushroom (Agaricus bisporus) cultivation includes a highly complex microbiome. The aim of the study was to evaluate ecological interactions (synergistic, antagonistic, or additive) between a commercial population of the entomopathogenic nematode Steinernema feltiae (EPN) and beneficial microorganisms, bacterium Bacillus amyloliquefaciens B-241 (BA) or actinobacterium Streptomyces flavovirens A06 (SF). Their relationships were evaluated in efficacy against the pathogenic fungus Trichoderma aggressivum and the fungus gnat Lycoriella ingenua. Moreover, their impact on mushroom yield was estimated. The synergy factor was calculated as the ratio of observed to expected values regarding their efficacy against T. aggressivum/L. ingenua and influence on mushroom production. Additive relationships in efficacy against T. aggressivum were observed between EPN and BA or SF. As for the impact on yield, synergistic interactions were indicated between each beneficial microorganism and EPN. Considering suppression of L. ingenua, a mild antagonistic reaction between EPN and each beneficial microorganism was observed in plots without T. aggressivum and additive in plots inoculated with the pathogenic fungus, although high efficacy was achieved in all combinations (>80%). Tested native strains of both beneficial microorganisms could be combined with the commercial EPN strain for successful biological pest and disease control in mushroom production.