Table 1. Summary of selected studies that have demonstrated direct and indirect effects of increased temperature and CO₂ on chemically mediated tritrophic interactions, as illustrated in Figure 1. “Path” refers to the letters included as path coefficients in Figure 1.

Path	Relevant direct and indirect trophic interactions
A	Direct effects of increased temperature on plant biomass are often positive [65].
B	High temperatures can have direct negative effects on natural enemy survival [8]–[9].
C	Elevated temperatures can decrease larval development time [12], [15].
D	Increased temperature can cause increased production of sapogenins [66].
E	Faster developing larvae reduce their window of vulnerability to predators and parasitoids [67].Developmental asynchrony between host and parasitoid can result in high parasitoid larval mortality [68], [69].Changes in larval performance can affect natural enemies; poor host quality negatively affects parasitoids [70].
F	Herbivore larvae consume plant tissues, reducing biomass [71]. This reduction in biomass is increased by other factors: elevated CO2 can increase consumption rate and total plant biomass removed, and herbivores can increase consumption rates to compensate for poor leaf quality [19], [20], [24].
G	The trophic cascade. Enemies have an indirect positive effect on plant biomass via controlling heribivory [72].
H	Elevated CO2 directly increases plant growth by increasing photosynthesis [15]–[18], [24].
I	Elevated CO2 reduces plant quality by increasing some carbon based defenses or by decreasing plant N content [19]–[24].
J	Poor leaf quality due to elevated CO2 can negatively affect herbivore performance [20], [26].
K	There is a trade-off between investing resources in plant defense versus growth [34].
L	Saponins are derived from sapogenins and concentrations are positively correlated.