Study finds wild nematode worms learn to avoid harmful bacteria—and their offspring inherit this knowledge

gene expression in the worm’s nervous system. The researchers hypothesize that the reason the behavior ceases after a few generations is that the response also causes the worms to avoid a helpful bacterium, Pseudomonas mendocina, which is a good food source.

The new findings provide proof of principle that the transgenerational inheritance previously observed in the lab likely benefits nematodes in the wild as well. The study also adds to our understanding of how small molecules from bacteria can regulate interactions between the bacteria and their worm hosts.

The researchers propose that identifying bacterial small molecules with similar effects will allow us to further explore this new type of bacteria-host interaction and its role in worm survival.

The authors add, “Here, Sengupta and colleagues report that a pathogenic bacterial species found in C. elegans’ natural environment, Pseudomonas vranovensis, induces learned avoidance behavior and four generations of transgenerational inheritance of avoidance in worms through a single small RNA.

“Worms exposed to this small RNA (Pv1) not only avoid the pathogen, but also other beneficial bacteria (Pseudomonas mendocina), suggesting ecological trade-offs for such heritable behaviors in the wild that may lead to the cessation of avoidance after several generations.”