Assessment of the olfactory response to chemicals or bacteria in pristionchus nematodes

INTRODUCTIONIn the soil environment, nematodes must rely on a number of host-specific chemical cues in order to find potential beetle hosts. They must also discriminate among different food choices (i.e., bacteria), which is important because if the nematodes concentrate on an unsuitable food source, they may die. To detect the bacteria and host-specific chemicals, nematodes use sensory structures called amphids and phasmids that are located on the head and tail, respectively. The olfactory response of nematodes can be studied in the laboratory using the very simple agar-based assay described here. This assay determines the attractiveness of Pristionchus to a range of beetle-associated compounds and has allowed detailed molecular mechanisms of olfaction to be studied in Pristionchus. It can also be used to examine the food choice of these nematodes when they are faced with a number of bacteria.