Data from: Water-repellent plant surface structure induced by gall-forming insects for waste management

Many animals and plants have evolved elaborate water-repellent
microstructures on their surface, which often play important roles in
their ecological adaptation. Here we report a unique type of
water-repellent structure on plant surface, which develops as an
insect-induced plant morphology in a social context. Some social aphids
form galls on their host plant, in which they produce large amount of
hydrophobic wax. Excreted honeydew is coated by the powdery wax to form
“honeydew balls”, which are actively disposed by soldier nymphs through an
opening on their gall. These activities are enabled by a highly
water-repellent inner gall surface, and we discovered that this surface is
covered with dense trichomes that are not found on normal plant surface.
The trichomes are coated by fine particles of the insect-produced wax,
thereby realizing a high water repellency with a cooperative interaction
between aphids and plants. The plant leaves on which the gall is formed
often exhibit patchy areas with dense trichomes, representing an ectopic
expression of the insect-induced plant morphology. In the pouch-shaped
closed galls of a related social aphid species, by contrast, the inner
surface was not covered with trichomes. Our findings provide a convincing
example of how the extended phenotype of an animal, expressed in a plant,
plays a pivotal role in maintaining sociality.