Attraction of second-stage juveniles of Meloidogyne species to fluopyram.

Abstract

Several benzenoid aromatic compounds were found to attract second-stage juveniles (J2) of Meloidogyne species in previous studies. Here, the attraction of Meloidogyne J2 to the nematicides fluopyram and fluensulfone, with and without aromatic attractants, was evaluated on agar plates and in sand. Fluensulfone mixed with 2-methoxybenzaldehyde, carvacrol, trans-cinnamic acid, and 2-methoxycinnamaldehyde, attracted Meloidogyne javanica J2 on an agar plate, whereas fluensulfone alone did not. In contrast, fluopyram alone attracted J2 of M. javanica, Meloidogyne hapla, and Meloidogyne marylandi, although higher numbers of M. javanica J2 were attracted to the nematicide with the aromatic compounds. Trap tubes loaded with 1 and 2μg fluopyram attracted M. javanica, Meloidogyne incognita, M. hapla, and M. marylandi J2 in the sand. Fluopyram-treated tubes attracted 4.4-6.3 times higher numbers of M. javanica and M. marylandi J2 than fluensulfone. Potassium nitrate (KNO3 ), a Meloidogyne J2 repellent, did not abolish fluopyram's attractiveness to M. marylandi. These results indicate that high numbers of Meloidogyne J2 near fluopyram on an agar plate or in sand are caused by the attractiveness of the nematicide and not by the accumulation of dead J2 after their random encounter with the nematicide. Aromatic attractants have the potential to attract Meloidogyne J2 to nematicides; however, fluopyram itself was attractive to Meloidogyne J2. The attractiveness of fluopyram to Meloidogyne J2 might contribute to its high control efficacy, and elucidation of the attraction mechanism could be useful for nematode-control strategies. © 2023 Society of Chemical Industry.