The project will investigate the ability of insects to detect and respond to infrared light, which is a type of electromagnetic radiation with wavelengths longer than that of visible light. It is known from insects as diverse as honeybees, beetles and butterflies that animals have evolved diverse strategies to perceive and utilize electromagnetic waves. Organs evolved for perceiving or controlling electromagnetic waves often surpass similar man-made devices in both sophistication and efficiency. To date, most of the focus in this area of research has been on the abilities of insects to perceive shorter wavelengths of light; much less is known about how animals respond to longer wavelengths, in part because the tools to investigate this end of the spectrum have only recently become commonly available. In this research, physicists and biologists will collaborate in studying a few model systems, including the antennae of moths and specialized wing scales of butterflies, to understand how insects can perceive and utilize infrared light. Understanding and harnessing natural design concepts through "biomimicry" will deepen our knowledge of complex biological systems and inspire ideas for creating new technologies. The research will provide training opportunities in nanotechnology for graduate students in biology and physics.
The objectives of the project are to understand the physical mechanisms underlying the ability of insects to perceive and respond to infrared light, and to obtain engineering insights that can be used to create novel infrared materials, devices and systems. Infrared signals may play a critical and underappreciated role in a wide variety of insect behaviors. This project will provide a quantitative understanding of insects' abilities to sense and respond to broadband thermal radiation and narrowband fingerprint infrared radiation by analyzing two systems: (1) Scent pads and patches on the wings of butterfly species in the hyperdiverse tribe Eumaeini (Lepidoptera: Lycaenidae) that show extremely broadband, close-to-unity absorptivity/emissivity, and (2) Specialized sensilla on the antennae of different moth species that are able to capture infrared light with high wavelength-specificity and efficiency. The model insects will be studied using a multidisciplinary research platform. The infrared-sensing organs will be identified using single-sensillum electrophysiological recordings and behavioral bioassays with spectrally and temporally controlled infrared stimulation. The morphology of the infrared-sensing organs will be studied using scanning electron microscopy and X-ray micro-tomography. The optical properties of the sensilla will be studied using Fourier transform infrared spectroscopy, infrared microscopy, and finite-difference time-domain electromagnetic wave simulations. High-fidelity replicas of the infrared-sensing microstructures or their scaled models will be fabricated using nano- and micro-fabrication to systematically analyze how material properties, structures and arrangement of the sensilla affect the sensitivity and wavelength-specificity of infrared detection. Detailed studies of the mechanisms by which insects perceive and respond to infrared signals have not been carried out before, and a greater understanding of this phenomenon is likely to catalyze a new area of research for the scientific community. The project will expand our understanding of how natural selection can shape exquisitely adapted behaviors and structures.