it might help to be a bit more specific on which plant you are talking about

https://en.wikipedia.org/wiki/Dipladenia

All I have is the plant stick from my neighbour. It says Rio Red.

Dipladenia/Mandevilla are considered the same by some but Mandevilla has larger flowers. Rio Dipladenia also comes in white and pink from what I read. Yes Japanese beetles will go for them and many other plants.