In vitro reproduction of Pratylenchus neglectus on carrot discs and investigation of its interaction with Meloidogyne hispanica on potato

Root-lesion nematodes, Pratylenchus spp., and root-knot nematodes, Meloidogyne spp., can occur concomitantly in potato fields and the interactions between the two groups of plant parasitic nematodes (PPN) may represent a threat to the potato crop. The in vitro reproductive fitness of 3 Portuguese isolates of P. neglectus isolated from potato fields was assessed using monoxenic carrot disc cultures inoculated with 10 females and maintained at 25 °C. The three isolates were able to reproduce at 56 days after inoculation (DAI) and the final population densities were significantly increased at 84 DAI. The P. neglectus isolate with the best reproductive ability was further selected and the concomitant effects of P . neglectus and M. hispanica were investigated in a pot trial using potato ( Solanum tuberosum L.) cv. Agria as host. Single potato sprouts were inoculated with 250, 500, 750 and 1000 of either P. neglectus mixed stages/ M. hispanica second-stage juveniles, or a combination of both nematodes. At 60 DAI, nematodes were extracted from roots and soil, the final population densities determined, for both nematode species, and the reproductive factor calculated. The experiment was run twice. The results suggest an additive effect of M. hispanica on P. neglectus reproduction, although future tests are still needed to confirm the possibility of an increase of P. neglectus population densities for the next crop, when both nematodes are inoculated concomitantly. The information obtained reinforces the need for a careful monitoring of these two PPN species in potato crops.