Fungal pathogen and ethanol affect host selection and colonization success in ambrosia beetles

Abstract

AbstractAmbrosia beetles exhibit broad host ranges but a narrow preference based on the condition of the host. Tissues infected by pathogens or containing ethanol can facilitate attacks by ambrosia beetles, although it still remains unclear how these factors interact.The present study aimed to examine how (i) chestnut logs infected with the fungal pathogenCryphonectria parasiticaand treated with ethanol (i.e. baited with ethanol lure, soaked in ethanol or untreated) and (ii) hornbeam logs soaked in different ethanol concentrations (3–12.5%) affect host selection and colonization success of ambrosia beetles.Ethanol‐soaked logs were more attractive toAnisandrus disparthan ethanol‐baited logs or untreated logs, although this difference was more evident in uninfected than infected logs. Increasing ethanol concentration in host tissues was differentially attractive toXyleborinus saxeseniiandXylosandrus germanus. A nonlinear relationship was also documented between ethanol concentration and emergence ofX. germanusadults.Overall, the results obtained suggest that the presence ofC. parasiticain chestnut logs can affect host selection in ambrosia beetles. In addition, the ethanol concentration in tree tissues affects host selection and colonization success, although the effect varies depending on the beetle species. This contrasting response could be a niche‐partitioning mechanism based on ethanol within host tissues.