I've got a mandevilla vine that I've recently brought indoors for the
fall/winter. We're in a zone 7/8 area (southwestern B.C., Canada). The
temperatures have been dipping to about 40°F overnight. Since I've brought
it in, the leaves and flowers have been falling off, some of the leaves are
turning yellow, others have black areas on them. I'm unable to find any
kind of bugs on the plant. It was in a semi-shaded area in the house and
I've just moved it to a brighter spot. Does anyone have any ideas about
what might be wrong?

Thanks in advance,
Brenda