Efficacy of Two Entomopathogenic Nematode Species as Potential Biocontrol Agents against the Diamondback Moth, <I>Plutella xylostella</I> (L.)

Abstract

The diamondback moth, <em>Plutella xylostella</em> (L.) (Lepidoptera: Plutellidae) is an important pest of cruciferous crops in Iran. The susceptibility of <em>P. xylostella</em> larvae to two species of entomopathogenic nematodes (EPNs) (<em>Steinernema carpocapsae</em> and <em>Heterorhabditis bacteriophora</em>) was examined under laboratory conditions. Leaf bioassays were conducted to evaluate the nematode's capability to reach the larvae and kill them. High larval mortality (72.6-96%) was observed in laboratory experiments. The ET<sub>50</sub> of <em>H. bacteriophora</em> was higher than that of <em>S. carpocapsae</em>. The ET<sub>50</sub> of entomopatpgenic nematodes, <em>H. bacteriophora</em> and <em>S. carpocapsae</em> tested ranged from 21 to 139.7 and 11.3 to 71.4 hours, respectively. The effect of both factors infective juveniles (IJs) and exposure time of 50% (ET50) on the larval mortality was significant (df = 6; P < 0.001) and (df = 2; P < 0.001), respectively. This study revealed that entomopatogenic nematodes (EPNs) have great potential that should be exploited in diamondback moth, <em>P. xylostella</em> management.