Lineage-specific patterns of sexually dimorphic antennal transcription in the paper wasp Polistes fuscatus.

Abstract

Olfaction mediates many behaviors in social Hymenoptera, with sexual dimorphism in antennal transcription associated with different behaviors between sexes. Females display coordinated social behaviors within colonies, while males exhibit limited social behavior but are selected for finding mates. The expanded "9-exon" odorant receptor (OR) gene subfamily is associated with chemical communication and exhibits strongly female biased antennal transcription in ants and honey bees. Polistine wasps represent an independent evolution of sociality and associated expansion of 9-exon ORs, though antennal expression patterns are unknown. Here, we report distinct patterns of sexually dimorphic OR transcription in Polistes fuscatus compared to ants and bees. Most P. fuscatus 9-exon transcripts were detected at similar levels in males and females, and some were male biased. We also report differential antennal transcription of cytochromes P450 and muscle-related genes between sexes. We discuss these patterns in the context of the unique sexual and social behaviors of Polistes wasps, including prolonged male mating aggregations and male antennal tapping and curling during courtship and copulation. These results call attention to the lineage-specific selective pressures shaping sexually dimorphic antennal transcription in social insects.