Aromatic compounds that attract Meloidogyne species second-stage juveniles in soil

Nematode attractants could serve in nematode control strategies by combining with chemical or biological nematicides or by interrupting the nematodes' host-finding process. The attractiveness of some benzenoid aromatic compounds, mainly benzoic acids, alcohols, aldehydes and phenols, to second-stage juveniles (J2) of four Meloidogyne species (M. hapla, M. incognita, M. javanica and M. marylandi) was evaluated by using trap tubes and balls filled with washed dune sand buried in nematode-inoculated sand in Petri dishes.

Two-methoxybenzaldehyde, 2-methoxycinnamaldehyde, 2-hydroxybenzoic acid (salicylic acid), 2-hydroxy-3-methoxybenzaldehyde (o-vanillin), 3-methoxybenzoic acid, 4-methoxybenzoic acid and trans-cinnamic acid effectively attracted J2 of all or most of the four Meloidogyne species to trap tubes in a one-compound assay. When nematodes were exposed to three different compounds simultaneously in the three-compound assay, J2 of all Meloidogyne species were attracted mainly to 2-methoxycinnamaldehyde, salicylic acid and 4-methoxybenzoic acid. Exceptions were M. hapla J2, which were not attracted to salicylic acid. In the soil column assay, M. javanica and M. incognita J2 were attracted upward to 4-methoxybenzoic acid in a trap ball located 4 or 8 cm above the inoculation point, whereas salicylic acid and 3-methoxybenzoic acid demonstrated slight, if any attraction.

Although some of the tested compounds exist in root exudates, it is not clear whether they are involved in the nematode host-searching process in nature. The attractants found in the study have potential for use in Meloidogyne species control, probably as a nematode trap constituent or as compounds that disrupt the nematodes' host-finding process. © 2021 Society of Chemical Industry.