Gross anatomy of the visual processing centers of Hieroglyphus banian

Abstract

Hieroglyphus banian (H. banian) is a grasshopper species, endemic to South Asia. The optic lobe in Acrididae has been characterized to a great extent in orthoptera, predominantly using Locust species like Schistocerca gregaria, Schistocerca americana, and Locusta migratoria, which are closely related to each other. In this work, we characterize the anatomical features of the optic lobe and associated pathway in the grasshopper species H. banian using tract tracing, immunohistochemistry, and intracellular fills. All the areas of the visual pathways that have been reported in the other orthoptera species could be identified in H. banian. Visual pathways exhibited similar structure and connectivity as shown in immunohistochemistry and tract-tracing results supporting the conservation of these features across species within Acrididae. Two new structures in the posterior protocerebrum, PS1 and PS2 with prominent innervations from the optic lobe were identified. Novel structure PS1 is innervated from medulla via PS1T and, PS2 from aMe via PS2T, both new tracts we have identified.

Keywords: Insect visual system; Lobula; Optic lobe; Visual pathway.