Threadworms are versatile research objects and are excellent models for investigating fundamental evolutionary principles. Researchers at the Max Planck Institute (MPI) for Developmental Biology use the Caenorhabditis and Pristionchus threadworm genera to study the molecular mechanisms of biodiversity.
But how do the nematodes find “their” beetle. Certainly not by using the classical sensory organs, because nematodes have neither ears, nor hearing or common olfactory organs. Chemotactic experiments provide an answer. “We have investigated how beetles find their partners using P. maupasi, a nematode species specialised in May beetles. We washed the beetles with dichloromethane and offered them this solution on a Petri dish that was placed nearby. The beetles moved towards the washing solution, but did not react to pure dichloromethane. We identified phenol as an active component, i.e. sexual attractant of May beetles,” said Sommer who has in the meantime identified the specific chemical attractants of several Pristionchus species. Sommer is now hoping to elucidate the molecular mechanisms that control the nematode-beetle relationship and why and how they developed during evolution. It still remains to be clarified whether the relationship is parasitic, mutualistic or symbiotic. “We also need to have a closer look at beetle larvae. It is possible that the more effective immune system of adult beetles keeps the nematode population low or inactive,” speculates Sommer, who plans to further investigate the development and evolution of nematodes using genetic screening.