1. Figure S1 Figure S1. European corn borer (ECB) oral secretions (OS) did not induce the expression of proteinase inhibitors in tomato and maize. (a) Relative expression of Protease Inhibitor2 (PIN2) in tomato leaves and (b) Maize Protease Inhibitor (MPI) in maize leaves, 24 h after wounding and application of 20 µl of water and ECB OS diluted with water (1:1). Unwounded plants were used as the control. Different letters above the bars indicate values that are significantly different from each other (ANOVA, P<0.05, LSD procedure). Error bars represent ± SE (N = 4). + Wounding ControlWater 0 1 2 3 a b Relative expression SlPIN2 (Log 10 ) b OS (a) 0.0 0.5 1.0 1.5 2.0 2.5 ControlWaterOS + Wounding Relative expression ZmMPI (Log 10 ) a b b (b)

2. Figure S2. Detection of fluorescent oral secretions (OS) from European corn borer (ECB) after eating 0.5 g diet spiked with Alexa 488. (a) Maize leaf fed upon by ECB fed control diet (b) Maize leaf with one fluorescent spot of OS (indicated by arrow) along the ECB fed site (c) Maize leaf which ECB fed upon but no OS was detected. Five maize leaves were examined after being fed upon by ECB that had eaten diet spiked with Alexa 488, and only one fluorescence was detected (d) Detection of fluorescence in ECB OS, and (e) feces. Figure S2 Merged Fluorescence microscopy (a) (c) (b) (d) (e) Light microscopy

3. Figure S3 0 3 6 9 ControlECB Ablated ECB Intact b a c Relative expression SlLOX D (a) 0 1 2 Control ECB Ablated ECB Intact Relative expression ZmLOX3 a b c (c) Relative expression ZmOPR2 0 1 2 3 Control ECB Ablated ECB Intact b a a (d) (b) 0 3 6 9 12 15 ControlECB Ablated ECB Intact Relative expression SlOPR3 b a c Figure S3. European corn borer (ECB) saliva induces transcript levels of jasmonic acid (JA) biosynthetic pathway genes in tomato and maize. (a) Relative expression of Lipoxygenase D (LOX D) and (b) 12-oxo-phytodecanoic acid reductase 3 (OPR3) in tomato leaves and (c) LOX3 and (d) OPR2 in maize whorls, 24 h after feeding with ECB intact and ablated spinneret. Uninfested plants were used as the control. Different letters above the bars indicate values that are significantly different from each other (ANOVA, P<0.05, LSD procedure). Error bars represent ± SE (N = 4).

4. Figure S4 0 20 40 60 80 100 TomatoMaize µg g -1 FW glucose a b (a) 0 1 2 3 Control PBSGlcGOXGlc + GOX Relative expression ZmMPI (Log 10 ) a b b b c (b) Figure S4. Exogenous application of glucose (Glc) and glucose oxidase (GOX) induce the expression of Maize Protease Inhibitor (MPI) in maize leaves. (a) Free glucose levels in tomato and maize leaves and (b) Relative expression of MPI in maize leaves, 24 h after wounding and application of 20 µl of PBS, Glc (1 mM), GOX (40 ng) and Glc + GOX. Unwounded plants were used as the control. For experiments (a) and (b), N = 5 and 3, respectively. Different letters above the bars indicate values that are significantly different from each other (ANOVA, P<0.05, LSD procedure). Error bars represent ± SE.