Parasitic worms alter earwig behavior and gene activity
European earwigs infected by the roundworm Mermis nigrescens often move toward open water, unlike uninfected earwigs. A new study examined gene activity in both host and parasite to understand this manipulation. The findings suggest the water-seeking behavior involves molecular changes in the earwig and the worm.
European earwigs normally avoid open water, even though many earwig species favor damp places. Past work found that those infected by the roundworm Mermis nigrescens instead move toward water. The new study compared uninfected earwigs with insects at early and late infection stages.
Using RNA sequencing, researchers measured activity for 12,876 earwig genes and 9,722 roundworm genes. They reported shifts in thousands of genes across infection stages. Infected earwigs showed raised activity in sensory and signaling pathways, while the worms activated transport and secretion genes, pointing to a molecular exchange between host and parasite.
The findings could deepen scientific understanding of parasite-host interactions, potentially informing future research on behavior-altering infections. Researchers in genetics, ecology, and pest biology may use such molecular clues to study similar systems. For the public, the story may illustrate how microscopic parasites can reshape animal actions, though any practical applications remain speculative and distant.