Plant-mediated effects on entomopathogenic fungi: how the olive tree influences fungal enemies of the olive moth, Prays oleae

Abstract

The community of entomopathogenic fungi associated with the olive moth Prays oleae is specific for each generation of this insect. The entomopathogen Beauveria bassiana is almost exclusive to the phyllophagous or leaf generation, whereas Paecilomyces formosa mainly occurs in the carpophagous or fruit generation. The main objective of this work was to evaluate olive plant-mediated effects on the development (germination, growth, sporulation and spore viability) of both entomopathogens. While B. bassiana was strongly inhibited by olives, P. formosa development was more restricted by leaves. These inhibitory effects were caused by both volatile and diffusible compounds produced by olives and leaves. Specifically, the effects of two leaf volatile compounds, (Z)-3-hexen-1-ol and (Z)-3-hexenyl acetate were studied. The results suggest that olive plant organs affect entomopathogens by controlling their abundance and function, which may partly explain the occurrence of a fungal species in a specific P. oleae generation.