It has been reported that the heterorhabditis nematodes were more virulent than steinernematid nematodes against larvae Phyllophaga bicolor (Melo et al., 2010). Read following paper for more information.
Melo, E.L, Ortega, C.A., Gaigl, A. and Bellotti, A. 2010. Evaluation of entomopathogenic nematodes for the management of Phyllophaga bicolor (Coleoptera: Melolonthidae). Revista Colombiana de Entomologia 36: 207-212.