Migration and penetration of Meloidogyne enterolobii and M. incognita in soil columns with tomato and marigold

Abstract

Root-knot nematodes (Meloidogyne spp.) can parasitize and reduce yields of nearly all agricultural crops. Although migration studies focus on the model species, M. incognita, there is little information about M. enterolobii, which has been a major threat for guava in Brazil. The vertical migration of second-stage juveniles (J2) of M. enterolobii and M. incognita was evaluated to determine the effect of good host and nonhost plants on nematode motility. Fourteen-cm long soil columns were constructed of PCV rings with Styrofoam cups containing a 4-week-old tomato or marigold (Tagetes patula) seedlings as plant stimuli; host-free cups were used as nontreated control. After inoculating 1000 freshly-hatched J2, the columns were placed in environmental chamber sets at 20 °C. The columns were disassembled at 3, 6, and 9 days after inoculation (DAI). The experiment was completely randomized block with four replicates. J2 were extracted from each ring and cup, while tomato and marigold roots were stained to observe J2 that penetrated roots. Data were subjected to repeated-measure MANOVA and chi-square test to compare J2 distribution along the columns. The migrations under tomato and marigold stimuli were comparable to those under host-free columns. Although both species migrated over 13 cm, M. enterolobii was more mobile than M. incognita. Juveniles of M. enterolobii infected tomato roots as early as 3 DAI, whereas marigold delayed nematode penetration. Our results show that two species of root-knot nematodes behave differently within the soil, and under the same conditions J2 of M. enterolobii migrate faster than M. incognita.