Sex‐specific antennal sensory system in the ant Camponotus japonicus: Glomerular organizations of antennal lobes

Abstract

Ants have well-developed chemosensory systems for social lives. The goal of our study is to understand the functional organization of the ant chemosensory system based on caste- and sex-specific differences. Here we describe the common and sex-specific glomerular organizations in the primary olfactory center, the antennal lobe of the carpenter ant Camponotus japonicus. Differential labeling of the two antennal nerves revealed distinct glomerular clusters innervated by seven sensory tracts (T1-T7 from ventral to dorsal) in the antennal lobe. T7 innervated 10 glomeruli, nine of which received thick axon terminals almost exclusively from the ventral antennal nerve. Coelocapitular (hygro-/thermoreceptive), coeloconic (thermoreceptive), and ampullaceal (CO2-receptive) sensilla, closely appositioned in the flagellum, housed one or three large sensory neurons supplying thick axons exclusively to the ventral antennal nerve. These axons, therefore, were thought to project into T7 glomeruli in all three castes. Workers and virgin females had about 140 T6 glomeruli, whereas males completely lacked these glomeruli. Female-specific basiconic sensilla (cuticular hydrocarbon-receptive) contained over 130 sensory neurons and were completely lacking in males' antennae. These sensory neurons may project into T6 glomeruli in the antennal lobe of workers and virgin females. Serotonin-immunopositive neurons innervated T1-T5 and T7 glomeruli but not T6 glomeruli in workers and virgin females. Because males had no equivalents to T6 glomeruli, serotonin-immunopositive neurons appeared to innervate all glomeruli in the male's antennal lobe. T6 glomeruli in workers and virgin females are therefore female-specific and may have functions related to female-specific tasks in the colony rather than sexual behaviors.

Transcriptomics and neuroanatomy of the clonal raider ant implicate an expanded clade of odorant receptors in chemical communication

“…These data were compared with data from Camponotus floridanus (27,32), because no sex-specific antennal RNAseq data are available for A. vollenweideri. Three-dimensional reconstruction of a clonal raider ant worker antennal lobe from confocal micrograph stacks revealed 493 glomeruli divided into seven clusters defined by diverging input tracts, similar to what has been described in other ants (32,37,38) (Fig. 4A, Table S1, and Fig.…”

“…S1). The clonal raider ant male, on the other hand, possessed only 121 glomeruli, even fewer than other ant males (32,38) (Fig. 4B, Table S1, and Fig.…”

Aggressive behavior in the antennectomized male cricket Gryllus bimaculatus

“…With regard to antennal sensory integration, mechanosensory neurons in the antennae are considered to project into the ventral area of flagellar afferents (vfa), which is located in the posterior deutocerebrum in the cricket (Staudacher and Schildberger, 2000). In the carpenter ant, the female-specific basiconic sensilla on the antennae that are responsible for detecting cuticular hydrocarbons project to specific glomeruli in the dorsomedial region of the antennal lobe (Nakanishi et al, 2010). A recent anatomical study indicated that the chemical and tactile information pathways from the antenna are definitely dissociated at least at the level of second-order neurons (Yoritsune and Aonuma, 2012), i.e.…”

Cephalic Microstructure and its role in Predation Biology of Myrmicaria brunnea on Antheraea mylitta

“…The antennal basiconic sensilla (SB) of fire ants, Solenopsis invicta are also known to function as contact chemoreceptors [32,33]. Nakanishi et al [15] categorized two types of trichoid sensilla along with the sensilla trichoidea curvata in C. japonicus which does not always respond to stimulation by alarm pheromones [31,34]. Thus, these may have a similar function in M. brunnea also.…”