Glomerular Organization in the Antennal Lobe of the Oriental Fruit Fly Bactrocera dorsalis

Abstract

The oriental fruit fly, Bactrocera dorsalis is one of the most destructive pests of horticultural crops in tropical and subtropical Asia. The insect relies heavily on its olfactory system to select suitable hosts for development and reproduction. To understand the neural basis of its odor-driven behaviors, it is fundamental to characterize the anatomy of its olfactory system. In this study, we investigated the anatomical organization of the antennal lobe (AL), the primary olfactory center, in B. dorsalis, and constructed a 3D glomerular atlas of the AL based on synaptic antibody staining combined with computerized 3D reconstruction. To facilitate identification of individual glomeruli, we also applied mass staining of olfactory sensory neurons (OSNs) and projection neurons (PNs). In total, 64 or 65 glomeruli are identifiable in both sexes based on their shape, size, and relative spatial relationship. The overall glomerular volume of two sexes is not statistically different. However, eight glomeruli are sexually dimorphic: four (named AM2, C1, L2, and L3) are larger in males, and four are larger in females (A3, AD1, DM3, and M1). The results from anterograde staining, obtained by applying dye in the antennal lobe, show that three typical medial, media lateral, and lateral antennal-lobe tracts form parallel connections between the antennal lobe and protocerebrum. In addition to these three tracts, we also found a transverse antennal-lobe tract. Based on the retrograde staining of the calyx in the mushroom body, we also characterize the arrangement of roots and cell body clusters linked to the medial antennal-lobe tracts. These data provide a foundation for future studies on the olfactory processing of host odors in B. dorsalis.

CRISPR‐mediated mutagenesis of the odorant receptor co‐receptor (Orco) gene disrupts olfaction‐mediated behaviors in Bactrocera dorsalis

“…In addition, the glomerulus number showed no significant difference between WT and BdorOrco −/− flies ( P > 0.05, Student's t ‐test). All measured flies contained 56–59 glomeruli, which was slightly less than the number previously reported (Lin et al ., 2018). This difference may be due to the reconstruction of 3D structure method and several blurred glomeruli boundaries.…”

The Sensory Machinery of the Head Louse Pediculus humanus capitis: From the Antennae to the Brain

“…These results contrast with the aglomerular ALs previously reported for a closely related species, the pigeon lice C. columbae (Phthiraptera: Ischnocera) (Crespo and Vickers, 2012). On the opposite side, head lice showed a rather simple AL compared to other insects, such as dipterans with around 50–70 glomeruli (Laissue et al., 1999; Fishilevich and Vosshall, 2005; Ignell et al., 2005; Riabinina et al., 2016; Lin et al., 2018, etc. ), bees with 160–200 (Arnold et al., 1985; Galizia et al., 1999; Roselino et al., 2015, etc.…”

Recent Advancements in Studies on Chemosensory Mechanisms Underlying Detection of Semiochemicals in Dacini Fruit Flies of Economic Importance (Diptera: Tephritidae)

“…Thus, a comprehensive understanding of the neural mechanisms of odor detection and processing requires an olfactory sensory map of the brain. Recently, glomerular organization in the antennal lobe has been described in B. dorsalis [158]. In total, 64-65 glomeruli were anatomically classified in both sexes using synaptic antibody staining.…”

“…Recently, glomerular organization in the antennal lobe has been described in B . dorsalis [ 158 ]. In total, 64–65 glomeruli were anatomically classified in both sexes using synaptic antibody staining.…”

“…The number of glomeruli was in the range of 50–70, in other dipteran species. By comparing male and female antennal lobes, eight glomeruli showing enlargement in males or females were identified [ 158 ]. As only males are strongly attracted to ME, it is of interest to know whether these sex-dimorphic glomeruli are involved in the recognition of ME.…”