Mandevilla

This is the second season this patio plant has resided with me.
It was much less interested in blooming this summer then last
summer.  I am not sure why, but I will need to haul it in once
again when frost threatens.  Then it will have to reside in my
sunroom til next summer.

I will have to spray it with some mixture before it comes in
for the winter to keep the insect population at bay.  I do not
want to use insecticides?  Any suggestions?????