In the past I presented published research papers that roses take care of the aphid problem themselves.

The present research presented in the Proceedings of the National Academy of Sciences puts the above behavior in terms of the chemistry of the plants immune system.

Also of interest (to me) is that Nature is using the same immune system chemistry in plants as it uses in animals: âÂÂGroEL was known previously to trigger immunity in animals,â said Kaloshian, a member of UC RiversideâÂÂs Institute for Integrative Genome Biology. âÂÂHowever, our finding that it induces immunity in plants is new."

http://ucrtoday.ucr.edu/22930

Here is a link that might be useful: link for above