Influence of Temperature On Reproduction of Bursaphelenchus Xylophilus and Pinus Sylvestris Mortality

In three separate experiments, one-year-old Pinus sylvestris seedlings were treated with either wound, wound + water, wound + Bursaphelenchus xylophilus culture filtrate, wound + 3,000 B. xylophilus, or unwounded controls and maintained at 15, 20 or 25°C for 340, 270 and 240 degree-days (DD-base 10°C) or 68, 27, and 16 days after inoculation, respectively. Bursaphelenchus xylophilus infected pines at all temperatures and nematode reproduction was similar and considerable at 20 and 25°C but low at 15°C. First pine death occurred at 215, 150 and 180 DD or 43, 15 and 12 days after inoculation at 15, 20 and 25°C, respectively. Visible symptoms and pine mortality at 20 and 25°C were correlated with the number of nematodes recovered from dead pines. At 15°C, nematode numbers were not correlated with visible symptoms. No control plants died in any of the experiments except that at 15°C which indicates that pine death at this temperature is not caused by nematodes alone. Furthermore, the data suggest that temperature increases B. xylophilus reproduction and possibly influences host physiology.

Affiliations: 1: Department of Biological Sciences, Simon Fraser University, Burnaby, Vancouver, British Columbia, Canada, V5A 1S6