Date of Award
Doctor of Philosophy (PhD)
Environmental Engineering and Earth Sciences
Peter H Adler, Committee Chair
Eric P Benson
The proboscis of butterflies and moths is a key innovation contributing to the high diversity of the order Lepidoptera. In addition to taking nectar from angiosperm sources, many species take up fluids from overripe or sound fruit, plant sap, animal dung, and moist soil. The proboscis is assembled after eclosion of the adult from the pupa by linking together two elongate galeae to form one tube with a single food canal. How do lepidopterans maintain the integrity and function of the proboscis while foraging from various substrates?
The research questions included whether lepidopteran species are capable of total self-repair, how widespread the capability of self-repair is within the order, and whether the repaired proboscis is functional. I demonstrated the capability of butterfly and moth species from families throughout the Apoditrysia to completely repair a totally separated proboscis. Generally, the repaired proboscis was capable of taking up fluid. Because self-repair is a process that has been modeled for nature-inspired designs of microfluidic devices, further questions involve the mechanisms used in repair. I found that labial palps, coiling, and wetting were not required for repair for Danaus plexippus and Vanessa cardui (Nymphalidae). Wing movements facilitated repair for V. cardui but not for D. plexippus.
Self-cleaning has applications in bioinspirational research. How is the proboscis kept clean and free of debris during foraging? I found bacterial inhibition by the proboscises of V. cardui and Agraulis vanillae (Nymphalidae) on poured plates inoculated with Bacillus sutbtilis and Pseudomonas aeruginosa. The adaptive value of self-repair and self-cleaning of the proboscis goes beyond continued uptake of fluids. Lepidopterans with separated galeae would be excluded from foraging from narrow flower corollas. Additionally, the ability to coil the proboscis would optimize the aerodynamics of flight by reducing drag. Structural or chemical features of the proboscis that resist bacterial contamination would help protect from infection.
Pometto, Suellen Floyd, "Self-Repair and Self-Cleaning of the Lepidopteran Proboscis" (2019). All Dissertations. 2452.