アリ社会に侵入する甲虫の擬態戦略を解明(Beetles Go Stealth Mode to Infiltrate Ant Societies)

2026-02-09 カリフォルニア工科大学(Caltech)

A Sceptobius rove beetle climbs aboard an ant to groom it and steal its scent, thereby gaining acceptance into the ant colony.Credit: Parker laboratory

<関連情報>

• https://www.caltech.edu/about/news/beetles-go-stealth-mode-to-infiltrate-ant-societies
• https://www.cell.com/cell/abstract/S0092-8674%2825%2901490-4
• https://www.cell.com/current-biology/abstract/S0960-9822(25)01413-7

生態学的ジレンマを通じた共生の定着 Symbiotic entrenchment through ecological Catch-22

Thomas H. Naragon ∙ Joani W. Viliunas ∙ Mina Yousefelahiyeh ∙ … ∙ Reto S. Wijker ∙ Alex L. Sessions ∙ Joseph Parker
Cell  Published:February 5, 2026
DOI:https://doi.org/10.1016/j.cell.2025.12.041

Highlights

• A rove beetle transcriptionally silences the biosynthesis of hydrocarbon pheromones
• The stealth beetle grooms ants, stealing hydrocarbons to infiltrate the ant society
• Ant hydrocarbons stop beetle desiccation, essentializing its attraction to ants
• Interdependent hydrocarbon silencing and ant attraction entrench the symbiosis

Summary

Why symbiotic organisms evolve irreversible dependencies on hosts is an outstanding question. We report a biological stealth device in a beetle that permits infiltration of ant societies. Via transcriptional silencing, the beetle switches off biosynthesis of cuticular hydrocarbons (CHCs)—body surface pheromones that function pleiotropically as a waxy desiccation barrier. Silencing transforms the beetle into a chemical blank slate onto which ant CHCs are transferred via grooming behavior, leading to perfect chemical mimicry and acceptance into the colony. Silencing is irreversible, however, forcing the beetle into a chronic dependence on ants to both maintain mimicry and prevent desiccation. We show that evolutionary reversion of the silencing mechanism would render the beetle detectable to ants; conversely, reversion of the beetle’s attraction to ants would render it desiccation prone. Symbiotic entrenchment can thus arise from epistasis between symbiotic traits, locking lineages into a Catch-22 that obstructs reversion to living freely.

根付いた共生関係の強制された特異性 Enforced specificity of an entrenched symbiosis

Julian M. Wagner ∙ Jason H. Wong ∙ Jocelyn G. Millar ∙ … ∙ Thomas H. Naragon ∙ James Q. Boedicker ∙ Joseph Parker
Current Biology  Published:December 5, 2025
DOI:https://doi.org/10.1016/j.cub.2025.10.066

Highlights

• A myrmecophile rove beetle detects host ant pheromones to find and infiltrate nests
• The beetle lives with one ant species in nature yet accepts diverse ants as hosts
• Specificity arises not from neural preference but from constraints on switching hosts
• Enforced specificity may be typical of entrenched symbiotic lifestyles in the Metazoa

Summary

The Metazoa encompasses inordinate lineages of symbionts and ecological specialists that obligately depend on particular hosts. The maintenance and fidelity of these lifestyles are often posited to hinge on sensory tuning to host-derived cues, a paradigm supported by studies of neural function in host-specific models. We experimentally reconstituted a socially complex relationship between an obligately symbiotic rove beetle and its single, natural host ant species, permitting us to probe its sensory basis. We show that cuticular hydrocarbons—the ant’s nestmate recognition pheromones—elicit host recognition by the beetle and the execution of ant grooming behavior, enabling the beetle to chemically mimic its host and infiltrate the nest as a parasitic impostor. The beetle also follows host trail pheromones, permitting inter-colony dispersal. Yet the beetle also performs these symbiotic behaviors with non-host ants separated by up to ∼95 million years, is able to socially assimilate into their colonies, and shows minimal sensory preference for its natural host over non-host species. Agent-based modeling reveals that the specificity of the beetle emerges not from sensory tuning but from physiological limits on dispersal and negative fitness interactions with alternative hosts, constraining the otherwise promiscuous beetle to its natural host. Recreating the in silico model with living insects empirically demonstrates specificity arising from these enforcing barriers. Our findings show how entrenched symbioses can obviate selection for taxonomically precise host recognition, with specificity emerging from forces external to the symbiont. Chance realization of latent compatibilities with alternative hosts may facilitate host switching, explaining the diversification and deep-time success of such taxa.