Efficacy and persistence of Heterorhabditis marelatus (Rhabditida: Heterorhabditidae) against root weevils (Coleoptera: Curculionidae) in strawberry

We compared the efficacy of Heterorhabditis marelatus Liu & Berry, a newly described species of entomopathogenic nematode, with that of H. bacteriophora Poinar against the root weevils, Ptiorhynchus ovatus (L.) and O. sulcatus in strawberry In the laboratory, H. marelatus was significantly more virulent than H. bacteriophora on O. ovatus and O sulcatus 7 d after nematode application at 14 degrees C. In field experiments, H. marelatus applied at concentrations of 52 and 136 infective juveniles (IJs) per square centimeter, reduced root weevil larvae and pupae 75.3 and 77.4%, respectively, 20 d after nematode application. H. bacteriophora applied at concentrations of 128 and 379 IJs per square centimeter reduced root weevils 50.0 and 74.0%, respectively. Both nematode species were detected up to 30 d after application by baiting with Galleria mellonella larvae in soil samples collected from the field.