Potential of Native Entomopathogenic Nematodes (Steinernematidae) as Biological Control Agents of Tetranychus urticae Koch

The two-spotted spider mite (Tetranychus urticae Koch) (Acari: Tetranychidae) is one of the most widespread and destructive phytophagous mite species, occurring across all climatic zones worldwide. Currently, the control of spider mites in crop protection relies primarily on chemical acaricides. However, the selection of resistant populations to their active ingredients is reducing their efficacy. The aim of the present study was to assess the susceptibility of T. urticae to a native isolate of entomopathogenic nematodes, Steinernema feltiae Filipjev ZWO21, under laboratory conditions. The experiment was conducted using Petri dishes, each containing 22–28 adult T. urticae. Infective juveniles (IJs) of the nematodes were then applied at a dose of 8000 IJs per dish (±300 IJs per mite). Petri dishes with mites treated with nematodes were placed in a Sanyo incubation chamber at 25 °C and 60% relative humidity. After three days, dead mites were collected from the Petri dishes and dissected, and mortality was subsequently determined. The present study confirmed that the S. feltiae ZWO21 isolate exhibited considerable potential for the biological control of T. urticae, causing 37.5–83.3% (mean 57.0%) mortality in this pest species. Although this result indicates a moderate efficacy when nematodes are applied alone, it also underscores the relevance of further research into their integration with other control strategies, including acaricides, within integrated pest management (IPM) programmes.