Effects of bacteria associated with pine wood nematode (Bursaphelenchus xylophilus) on development and egg production of the nematode

We tested the effects of four bacterial strains carried on the surface of the pine wood nematode (PWN), Bursaphelenchus xylophilus, on egg hatch, development rate and egg production. Strains GcM5-1A (Pseudomonas fluorescens) and ZpB1-2A (P. putida), were strong phytotoxin producers, while strains JnB1B (Pantoea sp.) and AcB1C (Peptostreptococcus asaccharalyticus) did not produce phytotoxins. None of the strains had any effect on egg hatch. GcM5-1A and ZpB1-2A promoted egg production, developmental rate, body length and diameter growth in both male and female PWN, whereas JnB1B and AcB1C had no such effects on the nematode. Indeed, the latter two strains completely inhibited egg production of the nematode. The results suggest that GcM5-1A and ZpB1-2A may provide PWN with food and/or essential nutrients for development and egg production. These results provide further evidence for our previous finding of a mutualistic symbiosis between the PWN and certain strains of bacteria carried by this nematode (Zhao et al., 2003, 2005).