Post‐inoculation Population Dynamics of Bursaphelenchus xylophilus and Associated Bacteria in Pine Wilt Disease on Pinus thunbergii

Abstract Population dynamics of the pine wood nematode Bursaphelenchus xylophilus (PWN) and its accompanying bacteria in non‐inoculated twigs along with the process of the disease was observed in Japanese black pine, Pinus thunbergii inoculated with PWN. In the non‐inoculated twigs, bacteria could be detected when only a few pine needles became yellow. Once most needles had turned yellow or brown, the nematode began to appear and the bacterial populations increased. At the late stages of the disease when the inoculated pine was dying and the needles were totally wilted, the populations of both nematode and bacteria started to increase rapidly. Only a few bacterial species were found at the early stages. As the disease process advanced, the bacterial populations increased rapidly in both population size and variety of the species. However, Pseudomonas fluorescens, P. sp., Pantoea sp. and Sphimgomenas pancimobilis, remained dominant.