New Strains of the Entomopathogenic Nematodes Steinernema scarabaei, S. glaseri, and S. cubanum for White Grub Management

White grubs possess natural defense mechanisms against entomopathogenic nematodes (EPNs). Hence, EPN isolates that naturally infect white grubs tend to be among the most effective biological control agents of white grubs. We tested the virulence of four EPN isolates recently isolated from infected white grubs in turfgrass areas in central New Jersey, USA against third-instar larvae of <i>Anomala orientalis</i>, <i>Popillia japonica</i>, and <i>Cyclocephala borealis</i>, which are pests of turfgrass and ornamental plants in the northeastern USA. Against <i>A. orientalis</i> and <i>P. japonica</i> larvae, the <i>Steinernema scarabaei</i> Ad and <i>S. scarabaei</i> SL isolates were highly virulent in laboratory tests, whereas <i>S. cubanum</i> HF was less virulent and <i>S. glaseri</i> SH the least virulent. None of the isolates caused high mortality of <i>C. borealis</i> larvae. EPN efficacy in greenhouse tests against <i>A. orientalis</i> followed the same pattern. The original isolate of <i>S. scarabaei</i>, the AMK001 strain, that had been maintained in the laboratory on <i>A. orientalis</i> and <i>P. japonica</i> larvae for 19 years showed the same virulence level against <i>A. orientalis</i> larvae as it did soon after its first isolation and was also as virulent as the fresh <i>S. scarabaei</i> Ad isolate; both isolates were more virulent than <i>S. scarabaei</i> SL. Future tests should determine the ability of these white grub-adapted isolates to provide long-term suppression of white grub populations.