I would recommend against using different forms of the conjunction "and" (or "et", "und", "y", "e", etc.) just to match the language of the publication. Doing so may look cute at first glance, but should cuteness be a factor in the construction of a list of references?
Anyway, I'm afraid that with the
apalike bibliography style it simply isn't possible to vary the language form of the conjunction particle within one and the same bibliography. If you decide it's necessary to use a connector other than the default form (the English "and"), you could do so as follows:
Find the file
apalike.bst in your TeX distribution, make a copy, and name the copy (say)
myapalike.bst. (Never edit an original file of the TeX distribution directly.)
Open the file
myapalike.bst in your favorite text editor and do a global search-and-replace for the string
" and ". (There should be two instances of this string, one in the function
format.names, the other in the function
format.lab.names.) Replace these strings with
" und " or whatever other form you believe to be most appropriate for your document.
Save the file
myapalike.bst, either in the directory where your main
.tex file is located or in a directory that's searched by BibTeX; if you choose the latter option, you will probably also need to update the filename database or your TeX distribution.
Start using the new style file via the instruction