Morphological assessment of the sensilla of the antennal flagellum in different castes of the stingless bee Tetragonisca fiebrigi

Abstract

The antennae of the insects have cuticular structures called sensilla that play a pivotal role in the perception of stimuli and in communication. The morphology of antennal sensilla has been characterized in eusocial bees; however, there is little information on bees of the genus Tetragonisca. Using scanning electron microscopy, 11 types of antennal sensilla were identified in Tetragonisca fiebrigi: trichodea (ST, subtypes I-VI), placodea, basiconica, coeloconica, ampullacea, and campaniformia. The largest diversity of sensilla was observed in females. The STI was the most abundant, followed by the placodea and the STII. The STI and the sensila placodea were more abundant in males than females, while the STII were more abundant in workers. Significant differences were found in the length of the different types of sensilla among the classes of individuals, with these differences being greater for the STI in males and the STV in queen; for the STII, STIII, and STIV in queen and workers; and for sensila placodea in queens, workers, and soldiers. Multivariate analysis (PCA and UPGMA) showed that the soldier subcaste was separated from the other females. This study advanced our understanding of sensilla morphology, including the number and distribution of sensilla across sexes and castes, and the sensory structures of T. fiebrigi. The results presented provide relevant information for elucidating the communication mechanisms of social insects.

Comparative Antennal Morphometry and Sensilla Organization in the Reproductive and Non-Reproductive Castes of the Formosan Subterranean Termite

“…Eusocial colonies consist of individuals that belong to different castes, with a limited number of individuals dominating reproduction and workers (and soldiers in some species) acting as helpers [ 4 ]. The antennal morphology and organization of sensilla often exhibit sex- and caste-specificity, reflecting differential sensory capabilities underlying the division of labor [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Sexual dimorphism is common in eusocial Hymenoptera (ants, wasps, and bees), where females are diploid, but males are haploid individuals that develop from unfertilized eggs.…”

Antennal Sensilla in Vespidae: A Comparison Between a Diurnal and a Nocturnal Polistinae Wasp

“…In A. flavissima and P. simillimus , trichoid-type 1 sensillum is more numerous than the other antennal sensilla, indicating the importance of mechanical stimuli perception in both species. High amounts of trichoid sensilla are reported in bees (Suwannapong et al, 2012; Fialho et al, 2014; Ravaiano et al, 2014; Month-Juris et al, 2020) and parasitoid Braconidae (Ochieng et al, 2000; Gao et al, 2007), showing the importance of tactile recognition for these organisms.…”

“…Insect antennae are the appendages with high sensilla concentration but they are not randomly distributed, as the number, size, and type of antennal sensilla vary according to sex and caste in social bees Melipona quadrifasciata Lepeletier, 1836 (Ravaiano et al, 2014) and Tetragonisca fiebrigi Schwarz, 1938 (Month-Juris et al, 2020), and altitude in Melipona scutellaris Latreille, 1811 (Nascimento et al, 2013).…”