Susceptibility of Polyphylla olivieri and Xanthogaleruca luteola to an entomopathogenic nematode, Heterorhabditis bacteriophora
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
Department of Plant Protection, Faculty of Agriculture, Azarbaijan Shahid Madani University, Tabriz, Iran,
چکیده
White grubs and Elm leaf beetle are two economically important major pests of landscapes and parks in the most cities of Iran. These pests detrimentally affect wide range of trees. Ecologists believe that establishing landscape and parks can be of advantage to the environment and provide conditions for healthier life. In such places chemical based control of pests is severely prohibited not only for environmental pollutions but also due to higher hazards and risks to human. Therefore replacing the pesticides with efficient environmentally friendly approaches has critical importance. White grubs are among the most destructive pests of landscapes and parks. Immature stages chew off the roots of plants. Depends on the host, white grub damage typically appears as stunted, wilted, discolored and death of plant. In the current study, two year old Polyphylla olivieri larvae were exposed to native isolate of an entomopathogenic nematode, Heterorhabditis bacteriophora in filter paper assay by which individual larva was subjected to 1 ml of two concentrations of infective juveniles (IJs) including 500 and 1000 IJs/ml. The experiment was run twice with four replications. Each replication included 10 individuals of white grub larvae. Mortality was recorded after 48 h at one day intervals for four days. Results revealed that larval mortality was non-significant between IJs concentrations. In filter paper assays recording mortalities at successive days were 40, 80, 80 and 100%, respectively. In another experiment, the elm leaf beetle, Xanthogaleruca luteola, was used in the experiments. Six day old larvae of elm leaf beetle were involved in leaf assay. Twenty four-well plates lined with 2 layers of filter paper were loaded with concentrations of 32.5, 65, 130, 260, 520 and 1040 IJs/L. Then individual larvae were added to each well. One 24-well plate was considered as a replication. The LC50-values were calculated using probit analysis at 36, 48 and 72 hours of larval exposure to the IJs. Recorded data were corrected for mortality using the untreated control data and subjected to analysis of variance followed by Duncan's mean separation test. LC values for mentioned period of times were 73.12, 34.71 and 10.93 IJs/L, respectively. These results showed that H. bacteriophora is a potent candidate to involve in further studies as biocontrol agent of two important pests of urban green spaces.
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