Woodmouse-help have I killed it?

For years I have had woodmice living and then just visiting my greenhouse(obvously not always the same mice they don't live that long) I have some lovely night shot video of them, beside a coin to show their size.I put a small pile of nuts on the table and each moring they have gone.

However three days ago I stored some horse chesnuts in the green house, one was nibbled-and no mice ever since! Please say horsechestnuts are not poisonous to mice.

 

isn't wild wonderful