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Updated: Mar 22, 2026

Rearing and Double-stranded RNA-mediated Gene Knockdown in the Hide Beetle, Dermestes maculatus
Published on: December 28, 2016
Patterns of molecular evolution of RNAi genes in social and socially parasitic bumblebees
Sophie Helbing1, H Michael G Lattorff2
1Institute of Biology, Molecular Ecology, Martin-Luther University Halle-Wittenberg, Hoher Weg 4, 06099 Halle (Saale), Germany.
Abstract:
The high frequency of interactions amongst closely related individuals in social insect colonies enhances pathogen transmission. Group-mediated behavior supporting immune defenses tends to decrease selection acting on immune genes. Along with low effective population sizes this might result in relaxed constraint and rapid evolution of immune system genes. Here, we show that antiviral siRNA genes show high rates of molecular evolution with argonaute 2, armitage and maelstrom evolving faster in social bumblebees compared to their socially parasitic cuckoo bumblebees that lack a worker caste. RNAi genes show frequent positive selection at the codon level additionally supported by the occurrence of parallel evolution. Their evolutionary rate is linked to their pathway specific position with genes directly interacting with viruses showing the highest rates of molecular evolution. We suggest that higher pathogen load in social insects indeed drives the molecular evolution of immune genes including antiviral siRNA, if not compensated by behavior.
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