Rohrscheib et al have a recent paper in Applied and Environmental Microbiology showing a new way that microbes can manipulate host behavior.
Male Drosophila inoculated with Wolbachia were found to engage in fewer aggressive behaviors than uninfected controls. In effect, Wolbachia transformed male fruit flies into pacifists. How does this happen? The mechanism of passive behavior caused by Wolbachia involves downregulation of octopamine, a neuropeptide that has been previously shown to modulate aggressive behavior in fruit flies.
Read the entire paper here:
Read the abstract here:
Wolbachia bacteria are endosymbionts that infect approximately 40% of all insect species and are best known for their ability to manipulate host reproductive systems. Though the effect Wolbachia infection has on somatic tissues is less well understood, when present in cells of the adult Drosophila melanogaster brain, Wolbachia exerts an influence over behaviors related to olfaction. Here, we show that a strain of Wolbachia influences male aggression in flies, which is critically important in mate competition. A specific strain of Wolbachia was observed to reduce the initiation of aggressive encounters in Drosophila males compared to the behavior of their uninfected controls. To determine how Wolbachia was able to alter aggressive behavior, we investigated the role of octopamine, a neurotransmitter known to influence male aggressive behavior in many insect species. Transcriptional analysis of the octopamine biosynthesis pathway revealed that two essential genes, the tyrosine decarboxylase and tyramine β-hydroxylase genes, were significantly downregulated in Wolbachia-infected flies. Quantitative chemical analysis also showed that total octopamine levels were significantly reduced in the adult heads.