Social environment affects sensory gene expression in ant larvae

Abstract

Social insects depend on communication to regulate social behaviour. This also applies to their larvae, which are commonly exposed to social interactions and can react to social stimulation. However, how social insect larvae sense their environment is not known. Using RNAseq, we characterized expression of sensory-related genes in larvae of the ant Formica fusca, upon exposure to two social environments: isolation without contact to other individuals, and stimulation via the presence of other developing individuals. Expression of key sensory-related genes was higher following social stimulation, and larvae expressed many of the same sensory-related genes as adult ants and larvae of other insects, including genes belonging to the major insect chemosensory gene families. Our study provides first insights into the molecular changes associated with social information perception in social insect larvae.

Brain and antennal transcriptomes of host ants reveal potential links between behaviour and the functioning of socially parasitic colonies

“…Our comparison of brain and antennal gene expression reveals a divergent transcriptome in host ants residing in the three experimental social environments. This mirrors what has been found in other systems where changes in the social environment, especially group size up to complete social isolation, strongly influenced gene expression in the brains of various hymenopterans (Lockett et al, 2016;Manfredini et al, 2021;Pulliainen et al, 2021;Scharf et al, 2021). We found the brain transcriptomes to be more affected by changes in the social environment (as evidenced by the number of DEGs) than the antennal ones.…”

“…This corroborates our earlier conclusion that even though these ants had never experienced their original colony as adults before, they still sense a difference when placed into a nest with non-related individuals. Similarly, in the ant Formica fusca, larvae were shown to be already able to distinguish between foreign and parasitic eggs and similarly showed shifts in sensory gene expression in response to their social environment (Pulliainen et al, 2019(Pulliainen et al, , 2021Schultner et al, 2013).…”

“…Other differences between parasitic and non‐parasitic nests, such as a general increase in aggression in parasitic nests, may nevertheless be transcriptionally detectable, for example, in the expression of stress‐related genes. Therefore, we specifically investigated genes related to sensory perception, in particular, odorant receptors, whose expression changes in response to the social environment of ant larvae (Pulliainen et al, 2021) and varies between workers mainly performing tasks inside or outside the nest (Caminer et al, 2023). Odorant receptors, particularly those of the 9‐exon gene family, are known to bind to cuticular hydrocarbons, which play an important role in communication in social insects (Pask et al, 2017; Slone et al, 2017).…”

Molecular characterization and expression variation of the odorant receptor co-receptor in the Formosan subterranean termite

“…formosanus showed that isolated workers did not differ in their antennal expression of Orco compared with those in groups of 15 or 100 ( Fig 5C ). Similarly, in the silky ant, Formica fusca , Orco was not differentially expressed between isolated larvae and those exposed to social cues, while many other chemosensory genes, such as OR s and OBP s, were upregulated upon social stimulation [ 73 ]. Taken together, while interactions with soldiers and nestmate workers are both important for the social life of termites, social cues indicating soldier presence and group size did not alter Orco expression in C .…”