Organization of the Auditory Pathway in Noctuoid Moths: Homologous Auditory Evolution in Insects

Abstract

The auditory pathways of insects at both the peripheral and central nervous system (CNS) levels have been described as conservative, with homologous tracts used for information transmission. The Orthoptera (crickets, katydids, and grasshoppers) has yielded considerable information regarding the neuronal circuitry of auditory systems and these data support the idea that certain CNS pathways appear pre-adapted for auditory processing. When using the comparative method for testing evolutionary hypotheses it is necessary to examine taxa that are phylogenetically disparate. Understanding the mechanics of hearing within one taxon (e.g., Orthoptera) may tell us something about the evolutionary pathways of that specific group but will not provide insights into the general principles of auditory evolution. To demonstrate homologous auditory evolution in all tym-panate insects the neural centers of phylogenetically distant taxa must be examined. Toward this end, the auditory pathway within the pterothoracic ganglion of the noctuoid moth (Lepidoptera) is described.