AbstractThe transmission of Bursaphelenchus mucronatus by its vector beetle, Monochamus saltuarius, was investigated. Fortythree beetles were reared individually under outdoor conditions and characteristics of their complete transmission curves of B. mucronatus were determined. The averaged nematode-transmission curves exhibited by beetles carrying more than 10 000, 1000 to 9999, and 100 to 999 nematodes at their emergence had a peak of 568, 146 and 12 nematodes per 5 days, respectively. The peaks appeared during a period from 20 to 30 days after beetle emergence. Backward stepwise regression analysis showed that the initial nematode load, the nematode departure efficiency and the nematode transmission efficiency had significantly positive influences on the number of nematodes transmitted into pine twigs. Other statistical analysis showed that the initial nematode load was most important among the three factors to account for the among-beetle difference in the number of nematodes transmitted, followed by the nematode transmission efficiency and nematode departure efficiency in that order. There were significant, positive correlations between the nematode departure efficiency, the nematode transmission efficiency and the number of nematodes transmitted from beetle into pine twigs.