Funding for this research was provided by:
Bayerisches Staatsministerium für Ernährung, Landwirtschaft und Forsten (W07 7831-22209-2013)
Deutsche Forschungsgemeinschaft (PR 292/12-1)
Received: 8 January 2018
Accepted: 14 March 2018
First Online: 2 April 2018
Ethics approval and consent to participate
: Not applicable; this study does not involve human subjects, human material, or human data.
: Not applicable.
: The authors declare that they have no competing interests.