Isolation and identification of entomopathogenic nematodes (Nematoda: Rhabditida) from the Eastern Black Sea region and their biocontrol potential against Melolontha melolontha (Coleoptera: Scarabaeidae) larvae

A survey was conducted for entomopathogenic nematodes in various agricultural fields in the Eastern Black Sea region of Turkey. A total of 77 soil samples were collected from 15 distinct geographic areas during 2010–2011. Seven entomopathogenic nematode isolates (ZET02, ZET04, ZET09, ZET28, ZET31, ZET35, and ZET76) were detected from the soil samples (9.1% positive) using the Galleria baiting technique. Morphological and molecular characterizations of the isolates were performed for species identification. Five isolates were identified as Heterorhabditis bacteriophora (ZET02, ZET04, ZET09, ZET28, and ZET35) and 2 isolates were identified as Steinernema feltiae (ZET31 and ZET76). The efficacy of all isolates was tested on Melolontha melolontha larvae in plastic boxes and pot experiments. Different concentrations of nematodes at 0, 500, 1000, or 2000 infective juveniles (IJs)/mL and 2 different temperature regimes (15 and 25 °C) were used. One hundred percent mortality was obtained from the ZET09 and ZET35 isolates at a concentration of 2000 IJs/mL at 25 °C. The same isolates also provided 100% protection with 100 IJs/cm2 in strawberry planted pot experiments.