Differential Response of <i>Meloidogyne enterolobii</i>, <i>M. floridensis</i>, <i>M. haplanaria</i>, and <i>M. incognita</i> to Sublethal Doses of Nonfumigant Nematicides

Root-knot nematodes (RKNs; <i>Meloidogyne</i> spp.) are among the most widespread and damaging plant-parasitic nematodes known. Although <i>M. incognita</i> is the most prevalent RKN species, other species, including <i>M. enterolobii</i>, <i>M. floridensis</i>, and <i>M. haplanaria</i>, have recently been detected in multiple Georgia, United States, vegetable fields. Producers use chemical nematicides to manage <i>M. incognita</i> populations because most vegetable crops do not have effective RKN host resistance. We evaluated the effects of sublethal doses of nonfumigant nematicides-fluazaindolizine, fluensulfone, fluopyram, and oxamyl-on motility, egg hatching, and reproduction of these four RKN species. In vitro behavioral response assays revealed significant variation in motility between species, with <i>M. enterolobii</i> being the less sensitive to the evaluated nematicides. RKN population response in greenhouse conditions indicated that all the nematicides impaired the reproduction of the evaluated <i>Meloidogyne</i> species. Whereas most nematicides displayed a strong effect on reducing the egg hatching, fluazaindolizine appeared to have a poor effect on suppressing the egg hatching across all RKN species. No differences were observed among <i>Meloidogyne</i> species in their egg-hatching responses to nematicides. In this study, we conducted the first comprehensive evaluation of these nematicides on motility, reproduction, and egg hatching in these RKN species. This study enhances our understanding of the species-specific responses of different <i>Meloidogyne</i> spp. to nonfumigant nematicides.