Upward migration of second-stage juveniles of Meloidogyne floridensis and M. incognita under different plant stimuli

The vertical migration of second-stage juveniles (J2) of Meloidogyne floridensis and M. incognita was investigated in segmented 14-cm long PVC soil columns having their top ring in contact with soil of a potted plant. Both bottom and top rings were screened appropriately to allow only upward nematode movement and preventing root penetration from the potted plant into the soil in the column. Plants used for nematode’s stimuli were the nematode attractive tomato ( Solanum lycopersicum L.) ‘Cobra’ and the nematode repellent French marigold ( Tagetes patula L.) var. Petite. Host-free columns were used as control. Columns with and without plants were placed in growth chambers at 20 °C and inoculated with each root-knot nematode species by injecting 1000 J2 through a hole in the basal ring of each column. Columns were dismantled at 3, 6 and 9 days after injection and J2 were extracted from soil of each ring and the planted pot; additionally, roots in the top pot were stained to observe J2 penetration. No preferential upward migration towards either plant stimuli was observed, but M. floridensis was more migrant than M. incognita , with 4.4% and 1.6% of active J2, respectively, reaching an upward distance of more than 13 cm regardless of plant stimuli. This study supports random migration of root-knot nematode J2, even without stimulus from a host plant.