Caste-biased patterns of brain investment in the subterranean termite Reticulitermes flavipes

Investment into neural tissue is expected to reflect the specific sensory and behavioral capabilities of a particular organism. Termites are eusocial insects that exhibit a caste system in which individuals can develop into one of several morphologically and behaviorally distinct castes. However, it is unclear to what extent these differences between castes are reflected in the anatomy of the brain. To address this question, we used deformation-based morphometry to conduct pairwise comparisons between the brains of different castes in the eastern subterranean termite, Reticulitermes flavipes. The dataset presented here consists of the confocal images of all the brains used in our analysis, separated by caste. Brains from five castes are presented - workers, soldiers, ergatoids, nymphs, and alates - which are further divided by sex.

Methods
Eastern subterranean termite, Reticulitermes flavipes, brains were dissected and immunostained using the commercially available antibody nc82, which stains at presynaptic active zones. Images were captured using a Leica SP8 DLS laser scanning confocal microscope at the Art & Sciences Imaging Center at the University of Kentucky. Whole brains were imaged at 1024x1024 pixel resolution using a 10x dry objective (HC PL APO 10x/0.40). Image stacks were generated by capturing images of brains at 1 μm intervals, which were saved as .TIF files. These image stacks were then imported into Fiji (https://fiji.sc/) and rotated so that all were oriented in the same direction. Black image slices were either added or removed to the beginning and/or end of each image stack so that the total number of image slices equaled either 150 or 160 (depending on caste). Image stacks that appeared faint were brightened by lowering the maximum display range in Fiji's "Brightness/Contrast" menu. Image stacks were then exported as .NRRD files to facilitate our pairwise comparisons of brain allometry.