Figure 3. Three identified salivary secretion phases into the plant during stylet penetration by aphids. (1) Gelling saliva (red arrows), forming the salivary sheath, (2) watery saliva (blue arrows), intracellularly secreted during brief stylet punctures (pd waveform), (3) watery saliva (purple arrows), into phloem sieve elements (E1 waveform), preceding phloem feeding. Salivation (3) might be mainly responsible for the induced resistance that is systemically spread, whereas salivation (1) and (2) may have more local effects.