Comparison of entomopathogenic nematodes efficacy on control of the elm-leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae) in vitro
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The elm tree (Ulmus glabra Huds.) is an ornamental plant used in many urban areas of Iran and is susceptible to more than 80 insect pest species. The most important insect pest of this tree is the elm leaf beetle, Xanthogaleruca luteola Muller which feeds on leaves in larval and adult stages. The aim of this study was to evaluate efficacy of different species of nematodes including Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora as biocontrol agents against the elm leaf beetle in laboratory conditions. This study was conducted using a factorial experiment based on a completely randomized design. The experiments were carried out at 27±2°C, 65±5% RH and 16 L:8 D photoperiods. Commercial isolates of three species of nematodes were provided from Koppert B.V. company of Netherland. All of three species of nematodes were reared on the last instar larvae of the greater wax moth, Galleria mellonella L. During the study, the responses of larvae and adult at 25±2°C were tested at different concentrations including 0, 100, 200, 300, 400, 500 IJ/ml (Infective Juveniles stage), in 9 cm Petri dishes containing filter paper soaked in 1 ml suspension of each nematode. Results showed that the highest mortality of third instar larvae which resulted from treatments with S. feltiae, S. carpocapsae and H. bacteriophora were 50.7, 46.1 and 37.6, respectively; these values for adult were 76.2, 56.5 and 60.0, respectively. The LC50 value of S. feltiae, S. carpocapsae and H. bacteriophora on the larvae were calculated 167.6, 218.2 and 338.7 IJ/ml, respectively. The LC50 value of S. feltiae, S. carpocapsae and H. bacteriophora nematodes on adult stage were determined 6.7, 204.1 and 70.3 IJ/ml, respectively. Also the LT50 value of S. feltiae, S. carpocapsae and H. bacteriophora nematodes on the larvae were calculated 44.5, 50.8 and 67.6, respectively. The LT50 value of S. feltiae, S. carpocapsae and H. bacteriophora nematodes on adult stage were determined 22.2, 36.2 and 34.7, respectively. Therefore, it can be concluded that among the three species of the studied nematodes, the S. feltiae species had the highest biocontrol effect on the elm leaf beetle.
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