Efficacy of a Native Entomophilic Nematode Isolate, Acrobeloides maximus, against Leopard Moth Borer Larvae under Laboratory Conditions

The objective of this study was to evaluate the biological traits of the native isolate (K29) of entomopathogenic nematode (EPN), Acrobeloides maximus, from Kerman region against the larvae of Zeuzera pyrina L. (Lepidoptera: Cossidae) the serious pest of walnut trees in Iran. Main purposes were determining the pathogenicity intensities in plate and branch, relationship between host body size and susceptibility to EPNs and reproduction and penetration potential of EPN. Plate assays were performed using a range of EPN concentrations (5, 10, 20, 50 and 100 infective juveniles (IJs) per larva) in laboratory. The LC50 of A. maximus K29 was 12.1 IJs larva-1 against Z. pyrina larvae after 72 h. This EPN caused high insect mortality in branch experiments and dissection of cadavers confirmed nematode infection. The addressing relation between host body size and susceptibility of larvae to nematode showed higher mortality rates in the larger larvae after exposing to A. maximus K29 isolate. The results of the penetration and reproduction assays indicated that A. maximus K29 was able to successfully penetrate and reproduce in the haemocoels of Z. pyrina and G. mellonella larvae. The highest reproduction was recorded at 20 IJs larva-1 in Z. pyrina (30560.5±559.3 IJs). In conclusion, our findings demonstrate that A. maximus K29, is virulent to Z. pyrina larvae and it causes infection and successfully recycles in this pest. Notwithstanding the effectiveness of this pathogenic agent on Z. pyrina larvae, further studies are required for better track of infection of treated larvae within the walnut tree trunks.