Comparative Biomechanics of Hawk Moths with Minute to Giant Proboscises and Diverse Feeding Habits

Among the most popular insects are the hawk moths, well known for their remarkably long proboscises and ability to feed from flowers with extraordinarily long nectar tubes containing nectar of variable viscosity, from watery to sticky. To understand the wide-ranging abilities of these moths to acquire fluid from long and short nectar tubes, a diverse team of researchers will investigate the structure, function, and biomechanics of the proboscis and its associated sucking pump.

The team will focus on how wettability of the proboscis and it ability to take up fluid enable the many species of hawk moths to feed on a wide range of liquid resources and from flowers with different nectar-tube lengths. By coupling structural and functional characteristics of the proboscises with principles of biology and fluid dynamics, the team will provide insights into the diversification of hawk moths and their coevolution with the different species of flowering plants from which they acquire nectar and, in turn, pollinate.

The results will provide strategies for novel bio-inspired engineering designs and products, such as new microfluidic probes. The resulting tools, techniques, and theories will be mutually beneficial for biological and engineering sciences and will involve integrated biological and engineering education of a new generation of scientists and teachers.

In addition, the researchers will participate in public outreach activities related to the project, and students will lead citizen-science activities that provide hawk moth specimens for study and share results on a student-created webpage.

This project focuses on how proboscis structure in hawk moths relates to biomechanics of feeding and explores the evolutionary forces responsible for miniaturization and gigantism of the proboscis. More than 1460 species of hawk moths have evolved to exploit diverse fluid resources. Their proboscis ranges in length from a fraction of body length to more than twice body length, allowing hawk moths to feed from many species of flowering plants.

The morphological structure of the tubular proboscis facilitates passive, spontaneous fluid uptake. The principal hypothesis is that structural variations of the proboscis and sucking pump provide physical determinants for diverse fluid-flow scenarios that enable hawk moths to use many liquid resources of different viscosities. Coupling morphology and wetting and transport properties of proboscises with biomechanics and energetics of fluid uptake will provide physical clues to the evolution and diversification of hawk moths.

The objectives are to investigate (1) proboscis structure in relation to wettability, (2) influence of permeability and proboscis geometry on fluid uptake, (3) sucking-pump morphology as a basis for fluid-mechanics modeling, and (4) evolution of physico-chemical traits and the constraints imposed by physical determinants of fluid flow. The research is based on unique materials characterization technology and high-speed microscopy of live moths, supported by theoretical modeling.

The team will include diverse talent and perspectives from all academic levels. Researchers will network with amateur lepidopterists to study hawk moths from around the country. Inspiration and skills exchanged between biologists and engineers will generate new techniques and approaches impacting biology, physics, and engineering.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.