(2nd Place) Morphological analysis of the antennal lobes in the brain of the Formosan subterranean termite

Subterranean termites are eusocial insects that rely on chemical signals to communicate. Olfaction is an essential sense for the adaptive social life of many insects, however, in termites, it remains largely unknown about how olfactory cues are perceived in the antennae and further processed in the central nervous system to elicit a behavioral response. Olfactory input from the antennae converges in the antennal lobes in the brain, where the axons of odorant sensory neurons interact with local interneurons to process the stimuli, and then send the signals to higher processing centers in the brain. In this study, we investigated if there are morphological differences in brain structures and antennal lobes among castes. We hypothesized that different castes have a different organization of the brain, which correlates with their behavioral division of labor. Our results showed that there are significant differences in the number of glomeruli on the antennal lobes across castes, along with the investment in antennal lobe volume relative to total brain size. Workers, nymphs, and reproductive alates have a comparable number of glomeruli, while soldiers and 5-year-old queens and kings have significantly fewer glomeruli. In addition, the structural investment in antennal lobe in relation to total brain size is significantly reduced in alates, as this caste has a greatly increased structural investment in the development of optic lobes for visual processing. Our results highlight the association between plasticity in brain development and division of labor in subterranean termites.