A survey was conducted for characterization and assess the biological traits of one selected native isolate of entomophilic nematodes from Kerman province against the larvae of the leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae), the serious pest of walnut trees in Iran. Morphological studies with light microscopy and scanning electron microscopy (SEM), as well as molecular analyses using the D2-D3 region of 28S rDNA, ITS and 18S rDNA identified this isolate as Acrobeloides maximus. After pathogenicity assessment in plate, the infectivity assays were performed in pots containing walnut seedlings and in infested walnut tree orchards. In plate assays, larval mortality was significantly influenced by concentration of the nematode and after 72h, the highest mortality of pest larvae was observed at the concentration of 200 IJs larva-1. The results of pathogenicity against Z. pyrina larvae in pots containing walnut seedlings and in infected walnut tree orchards indicated that this nematode was capable of reducing populations of pest in glasshouse and field experiments. Five days after nematode application, dissection of pest cadavers confirmed the presence of nematode in them. Our findings demonstrate that the free living A. maximus can infect the Z. pyrina larvae and successfully recycles. It may therefore be concluded that this biocontrol agent have good potential as a suitable candidates to utilize within IPM programs of this insect pest.

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