Comparative Movement Speed of Pathogenic and Nonpathogenic Isolates of Bursaphelenchus Nematodes

Abstract

Using a newly devised simple apparatus, comparative study was made on the movement speed of three Bursaphelenchus isolates : S1, a pathogenic isolate of Bursaphelenchus xylophilus ; S0, a nonpathogenic isolate of B. xylophilus ; M, a nonpathogenic isolate of B. mucronatus. Among these isolates, the M isolate moved fastest through the interspace between glass beads in the apparatus at all nematode densities examined. The S1 isolate moved slightly slower than S0 isolate at low densities, however, the former moved more quickly at high densities. Generally, the time required for the half number of nematodes to pass through the apparatus doubled when the interspace between beads was reduced by half. The threshold low temperature for movement was lowest in the M isolate, followed by the S1 and S0 isolate. Regarding the S1 and M isolates, the threshold low temperature for movement was lower than those for development.