Figure 2.

Cryofixed M. persicae aphid stylets in an Arabidopsis leaf. The stylet position illustrates the intimate contact between an aphid and the plant cell wall. Aphids usually do not disrupt cells, but maneuver their stylets through the apoplast and sample several cells along their way to the phloem. Cell wall penetration can take between 10 min and several hours and is accompanied by the secretion of gelling saliva. After arrival at a sieve tube, aphids start phloem feeding and usually keep their stylets anchored for hours or even days. This aphid reached the phloem in 15 min, after penetrating along a track of at least 26 μm of cell wall (not accounting for movements in the direction of the z plane) and showing 25 brief plasma membrane punctures along its path. The arrow indicates an abandoned tract with remnants of gelling saliva (toluidine blue staining, images of different depth of focus are separated with gray lines).