Evaluating the impact of some Steinernema feltiae (Filipjev, 1934) (Rhabditida: Steinernematidae) isolates on Cryptolestes ferrugineus (Stephens, 1831) (Coleoptera: Laemophloeidae) mortality and penetration

The rusty grain beetle, Cryptolestes ferrugineus (Stephens, 1831) (Coleoptera: Laemophloeidae) is a destructive pest in stored-product environments. This study evaluated the insecticidal efficacy of two Turkish isolates of the entomopathogenic nematode Steinernema feltiae (Filipjev, 1934) (Rhabditida: Steinernematidae) ST6 and TUR-S3-against adult C. ferrugineus under laboratory conditions in 2025 at the Nematology Laboratory of the Department of Plant Protection, Bursa Uludağ University. Infective juveniles (IJs) were applied at five concentrations (50, 100, 150, 200 and 250 IJs per petri dish), and both mortality rates and nematode penetration levels were recorded. Results revealed a clear dose-dependent increase in mortality for both isolates, with TUR-S3 achieving the highest mortality (93.33%) at 250 IJs, followed by ST6 (86.67%). Penetration rates also increased significantly with concentration, supporting a strong positive correlation between penetration and mortality (r=0.8113 for ST6; r=0.8850 for TUR-S3). Among the two, TUR-S3 consistently exhibited superior performance, obtaining higher virulence and infection efficiency. This is the first report demonstrating the pathogenicity of Turkish S. feltiae isolates against C. ferrugineus, underscoring their potential as eco-friendly biocontrol agents for integration into sustainable post-harvest pest management strategies.