Variation in the number of Bursaphelenchus xylophilus in aliquots of stock suspensions artificially inoculated on to subject pines

Abstract

AbstractThe procedures used to estimate the number of pine wood nematodes (Bursaphelenchus xylophilus) in stock suspensions and the variation in the number of nematodes in inocula applied to subject pine trees were examined. The findings suggest that preparing dilutions using 1 ml aliquots and making two replicate dilutions and three replicate counts of each dilution (or three dilutions and two counts) results in a precision of ±15% and an elapsed time for the majority of the population estimate procedures of less than 900 seconds. Under these conditions, the variation in the number of nematodes in the inocula was estimated to range from 55 to 156% of the intended population. This variation in the number of pine wood nematodes inoculated is unavoidable; thus, researchers should account for this variation when interpreting data from trials involving the artificial inoculation of pines.