The Hungry Fly: Hydrodynamics of feeding in the common house fly

TL;DR

This study uses advanced imaging and microsurgery to investigate the fluid dynamics of feeding in the house fly, revealing how its feeding pump operates efficiently under various conditions and comparing it across species.

Contribution

It introduces in-vivo imaging and perturbation techniques to analyze the feeding pump dynamics of the house fly, uncovering design principles and feedback mechanisms.

Findings

Fluid viscosity influences pump performance.

Stretch receptors regulate flow rate during feeding.

Common design principles identified across insect species.

Abstract

A large number of insect species feed primarily on a fluid diet. To do so, they must overcome the numerous challenges that arise in the design of high-efficiency, miniature pumps. Although the morphology of insect feeding structures has been described for decades, their dynamics remain largely unknown even in the most well studied species (e.g. fruit fly). Here, in the fluid dynamics video, we demonstrate in-vivo imaging and microsurgery to elucidate the design principles of feeding structures of the common house fly. Using high-resolution X-ray absorption microscopy, we record in-vivo flow of sucrose solutions through the body over many hours during fly feeding. Borrowing from microsurgery techniques common in neurophysiology, we are able to perturb the pump to a stall position and thus evaluate function under load conditions. Furthermore, fluid viscosity-dependent feedback is observed for optimal pump performance. As the gut of the fly starts to fill up, feedback from the stretch receptors in the cuticle dictates the effective flow rate. Finally, via comparative analysis between the housefly, blow fly, fruit fly and bumble bees, we highlight the common design principles and the role of interfacial phenomena in feeding.