How aphids lose their marbles

Area of Science:

• Entomology
• Biophysics
• Surface Science

Background:

• Insects navigate a world dominated by surface forces, facing risks of liquid entrapment.
• Waxy and hairy surfaces help insects avoid liquid entrapment, a challenge amplified in enclosed spaces like plant galls.

Purpose of the Study:

• To investigate the physical and physiological significance of wax secretion by aphids for managing excrement in plant galls.
• To understand the role of secreted wax in preventing liquid entrapment and facilitating waste removal.

Main Methods:

• Analysis of aphid-secreted wax properties.
• Microscopic examination of the inner gall surface.
• Observation of honeydew droplet behavior coated in wax.

Main Results:

• Aphid-secreted powdery wax is hydrophobic.
• The wax forms a microscopically rough, ultra-hydrophobic inner gall surface.
• Wax coating transforms honeydew droplets into mobile liquid marbles.

Conclusions:

• Aphid wax secretion is a 200-million-year-old solution to prevent liquid entrapment in plant galls.
• The wax serves multiple roles: hydrophobicity, creating an ultra-hydrophobic surface, and forming liquid marbles for efficient transport.
• This strategy highlights insect adaptation to surface forces in confined environments.