I know that these stimuli have to work together. I mean it is difficult to separate them and the bibliography about them is quite important. But if we combined in one experiment a relatively old plant, a virus infection and an aphid parasitoid, can these effects be additive? Virus infection sometimes changes the nutritional quality of a plant in order to beneficiate aphids. On the other hand, foraging behavior of parasitoids can increment aphid movement, but when the aphid is already parasitized, some aphid show lower movement capabilities. And an older plant has normally lower nutritional quality, inducing aphid to move out to more nutritional plants, but in presence of parasiotids, large plants may be a better place to hide from parasitization than younger ones, especially knowing that parasitoids females only expend a short period of time in each patch in order to increment their efficiency.

Are there any thoughts of these issues?