In vitro susceptibility of root-knot nematode populations (Meloidogyne spp.) from Crete, Greece to oxamyl and fenamiphos

Carbamate and organophosphate nematicides are routinely used for control of root-knot nematodes (RKN, Meloidogyne spp.) in greenhouses of Crete, Greece. Eleven populations of RKN were collected from greenhouses where such nematicides are intensively applied, but insufficient nematode control has been reported. Their susceptibility to fenamiphos and oxamyl was tested by estimating the percentage of immotile juveniles after 24-h exposure to five concentrations of each nematicide in 3.5-cm Petri dishes. Four populations collected from field crops without any recent history of nematicide application were also included in the study. Three populations maintained in pots for 3, 18 and 20 years without any exposure to nematicides served as controls. The estimation of LC₅₀ and resistant factor values indicated that the nematode populations from greenhouses, despite their intense exposure to nematicides, did not have reduced susceptibility to fenamiphos and oxamyl compared to nematode populations maintained in pots.