Estimation of virulence of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) based on its reproductive ability

Abstract

AbstractAs a means for estimating the virulence level of Bursaphelenchus xylophilus, we focused on its reproductive ability. Using six nematode isolates, which had high, intermediate or low levels of virulence, the number of nematodes that reproduced on Botrytis cinerea and in branch sections of Pinus thunbergii during 5 days was investigated. A significant positive correlation was found between nematode virulence and the number of nematodes reproducing either on the fungal culture or in the branch section. However, the rate of population increase with rise of virulence was clearly faster on the fungal culture than in the branch section. Our results suggest that the virulence level of B. xylophilus can be estimated approximately by evaluating the reproductive ability on B. cinerea or in branch sections of P. thunbergii tree. The effectiveness of branch section as a material for estimating the nematode virulence is discussed, taking into account the various factors associated with nematode virulence.