APA 6: How to get rid of the comma before "and [last author]"?

Question

I am using the document class APA 6 (\documentclass[man,a4paper,floatsintext,donotrepeattitle]{apa6}) and Biblatex (\usepackage[style=apa,sortcites=true,sorting=nyt,backend=biber]{biblatex}) to write my thesis. I adapted this to the German settings for APA 6 and it works quite well, but I can't get rid of the comma in these situations:

The highlighted section in yellow below is the one I don't want in the German citation version (for English APA6, it would be correct). Has anyone got an idea of how to get rid of these commas (in the text and in the bibliography)?

MWEB:

 \documentclass[man,a4paper,floatsintext,donotrepeattitle]{apa6}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}
\usepackage{csquotes}
\usepackage[style=apa,sortcites=true,sorting=nyt,backend=biber]{biblatex}
\DeclareLanguageMapping{german}{german-apa}
\usepackage{booktabs}
\DefineBibliographyStrings{ngerman}{
   andothers = {{et\,al\adddot}},}
\usepackage{hyperref}
\addbibresource{\jobname.bib}
\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}

@article{varazzani_noradrenaline_2015,
    title = {Noradrenaline and Dopamine Neurons in the Reward/Effort Trade-Off: A Direct Electrophysiological Comparison in Behaving Monkeys},
    volume = {35},
    issn = {0270-6474, 1529-2401},
    shorttitle = {Noradrenaline and Dopamine Neurons in the Reward/Effort Trade-Off},
    pages = {7866--7877},
    number = {20},
    journaltitle = {Journal of Neuroscience},
    author = {Varazzani, C. and San-Galli, A. and Gilardeau, S. and Bouret, S.},
    date = {2015},
    langid = {english}
}



\end{filecontents}
\shorttitle{Gedächtnisleistung und Pupillenweitung}
\begin{document}
Text \parencite{varazzani_noradrenaline_2015}
\printbibliography[heading=bibintoc]
\end{document}

Answer 1

As noted in the comments, this is fixed for more recent versions of biblatex-apa, but it's not too hard to make things work without upgrading.

You need to redefine \finalandcomma for the ngerman language:

\DefineBibliographyExtras{ngerman}{
  \def\finalandcomma{}
}

Also, I notice you have ngerman as your babel language, but then you instruct biblatex-apa to use german. Shouldn't they be the same?

If you want und instead of &, then add this to the preamble of the MWE below:

\AtEveryCitekey{%
  \renewcommand{\finalnamedelim}{%
    \ifnum\value{liststop}>2 \finalandcomma\fi\addspace\bibstring{and}\space}}
\AtBeginBibliography{\renewcommand*{\finalnamedelim}{%
    \ifthenelse{\value{listcount}>\maxprtauth}
      {}
      {\ifthenelse{\value{liststop}>2}
        {\finalandcomma\addspace\bibstring{and}\space}
         {\addspace\bibstring{and}\space}}}}

Here's my MWE. It works with your versions of biblatex, biber, and biblatex-apa. (It uses & instead of und, but I assume you've changed other things to deal with this, since & is hard coded in biblatex-apa.)

\documentclass[man,a4paper,floatsintext,donotrepeattitle]{apa6}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}
\usepackage{csquotes}
\usepackage[style=apa,sortcites=true,sorting=nyt,backend=biber]{biblatex}
\DeclareLanguageMapping{ngerman}{ngerman-apa}% <-- use ngerman mapping
\usepackage{booktabs}
\DefineBibliographyStrings{ngerman}{
   andothers = {{et\,al\adddot}},}
\DefineBibliographyExtras{ngerman}{% <-- redefine finalandcomma for ngerman
  \def\finalandcomma{}
}
\usepackage{hyperref}
\addbibresource{\jobname.bib}
\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}

@article{varazzani_noradrenaline_2015,
    title = {Noradrenaline and Dopamine Neurons in the Reward/Effort Trade-Off: A Direct Electrophysiological Comparison in Behaving Monkeys},
    volume = {35},
    issn = {0270-6474, 1529-2401},
    shorttitle = {Noradrenaline and Dopamine Neurons in the Reward/Effort Trade-Off},
    pages = {7866--7877},
    number = {20},
    journaltitle = {Journal of Neuroscience},
    author = {Varazzani, C. and San-Galli, A. and Gilardeau, S. and Bouret, S.},
    date = {2015},
    langid = {english}
}
\end{filecontents}
\shorttitle{Gedächtnisleistung und Pupillenweitung}
\begin{document}
Text \parencite{varazzani_noradrenaline_2015}
\printbibliography[heading=bibintoc]
\end{document}