Functional division of intrinsic neurons in the mushroom bodies of male Spodoptera littoralis revealed by antibodies against aspartate, taurine, FMRF-amide, Mas-allatotropin and DC0

The aim of this study was to further reveal the organization of Kenyon cells in the mushroom body calyx and lobes of the male moth Spodoptera littoralis, by using immunocytochemical labeling. Subdivisions of the mushroom bodies were identified employing antisera raised against the amino acids taurine and aspartate, the neuropeptides FMRF-amide and Mas-allatotropin, and against the protein kinase A catalytic subunit DC0. These antisera have previously been shown to label subsets of Kenyon cells in other species. The present results show that the organization of the mushroom body lobes into discrete divisions, described from standard neuroanatomical methods, is confirmed by immunocytology and shown to be further elaborated. Anti-taurine labels the accessory Y-tract, the γ division of the lobes, and a thin subdivision of the most posterior component of the lobes. Aspartate antiserum labels the entire mushroom body. FMRF-amide-like immunolabeling is pronounced in the γ division and in the anterior perimeter of the α/β and α′/β′ divisions. Mas-allatotropin-like immunolabeling shows the opposite of FMRF-amide-like and taurine-like immunolabeling: the γ division and the accessory Y-system is immunonegative whereas strong labeling is seen in both the α/β and α′/β′ divisions. The present results agree with findings from other insects that mushroom bodies are anatomically divided into discrete parallel units. Functional and developmental implications of this organization are discussed.