The influence of host and temperature on the vertical migration of Pratylenchus penetrans

The influence of both host and temperature on the vertical migration of Pratylenchus penetrans was examined in a series of experiments using maize, carrot, black salsify, pea, bean and potato. Plants were grown in a pot placed on top of a plastic pipe of variable length in a growth chamber. This pipe was planted into a second pot to maintain the humidity in the pipe. Nematodes were inoculated at the bottom of the pipe and were allowed to migrate upwards for 14 days after which the pipe was cut into 5 cm sectors from which the nematodes were extracted and counted. More nematodes migrated at 21 degrees C than at 16 or 11 degrees C. Migration of P. penetrans towards a host decreased with increasing distance between the nematodes and all hosts, with maize and bean eliciting the most attraction. They were the only hosts able to stimulate nematode migration up to the distal end of 31 cm pipes. Potato and carrot were the least influential hosts. Hosts differently influenced the migration only of second-stage juveniles (J2), with a greater percentage of J2 moving under maize and bean than under carrot. Under all hosts, adults migrated in greater proportions with increasing distance than did other stages. The attractiveness of hosts was age dependent. Generally, infectivity decreased with distance travelled by the nematode.