INCUBATION-TEMPERATURE AND TIME EFFECTS ON LIFE STAGES OF BURSAPHELENCHUS-XYLOPHILUS IN WOOD CHIPS

Wood chips of Pinus strobus inoculated with Bursaphelenchus xylophilus were incubated at 3, 12, 30, or 40 C during intervals of 47, 82, and 130 days to determine the effects of incubation temperature and time on total number of nematodes and occurrence of each life stage. Nematodes did not survive at 40 C; the greatest number of nematodes was maintained at 3 C. The number and percentage of juveniles in the propagative cycle were greatest at 3 C after 47 days, but the percentage was greatest at 30 C after 130 days. More third-stage dispersal larvae, with percentages as high as 85%, were extracted at 3 and 12 C than at 30 C by the end of the study. Dauer larvae were extracted from the chips, but percentages never exceeded 5%. The percentage of adults was greater at 30 C than at 3 and 12 C after 82 and 130 days. When a 1-week heat treatment at 30 C was applied to samples at 3 and 12 C, numbers and percentages of adults increased. Percentages of dauer larvae increased very slightly when the heat treatment was applied after 47 days, but numbers and percentages of juveniles and dispersals were affected erratically.