Colonization and pathogenicity for American and Chinese bacterial strains carried by pine wood nematodes.

Bacterial succession on the surface of pine wood nematode (PWN) may have a direct impact on the development of pine wilt disease (PWD). The objective of this study was to isolate bacteria from PWN in the United States where PWD was not a serious problem and compared with four bacterial strains (YG1，YG2，YG3，YG4) from China. Fifteen bacterial strains including seven dominant strains (MG3, MG4, MG5, MG8, MG9, MG11 and MG12) were isolated from 3 PWN originating in the USA. In competition assays, Four (MG4, MG5, MG8 and MG9) of the 15 American bacterial strains better colonized sterile PWN than all Chinese strains tested. These three American strains(MG5, MG8, MG9) were further compared with one reference Chinese strain(YG2) for control efficacy using Pinus thunbergii，P. massoniana，P. elliottii and P. tabuliformis as model systems. MG8 and MG9 provided better control of PWD caused by sterile PWN than YG2. These results show that two American strains MG8 and MG9 have great potential as biological control agents for PWD and deserve further studies.