Insecticidal and antifeedant activity of arugula Eruca sativa oil on elm leaf beetle Xanthogaleruca luteola Coleoptera: Chrysomelidae
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran,
چکیده
The elm leaf beetle Xanthogaleruca luteola (Müller), is one of the most destructive pests of elm trees in Iran. Arugula, Eruca sativa Mill, oil contains isothiocyanate compounds that exhibit insecticidal activity.In this research, the insecticidal and antifeedant activity of arugula oil was studied against elm leaf beetle under laboratory conditions at 25 ± 1 ºC, 75 ± 5% RH, and 16:8 h L:D. Eggs and larvae of elm leaf beetle were collected from the elms trees, where no pesticides were applied. Arugula oil was extracted by cold press method.LC50 values of the oil were studied in third instar larvae. In order to investigate the contact and digestive toxicity of the arugula oil, concentrations required for 50% mortality of population (LC50) were calculated and a preliminary experiment was conducted to find concentrations to cause 20 and 80% mortality. Then, the five concentrations were tested based on logarithmic intervals. The count of live and dead insects was assessed 24, 48 and 72 h post treatment. Then, nutritional indices were evaluated following 24, 48 and 72 h post feeding at LC50 level. Samples were placed in oven at 65 °C for 48 h to obtain the dry weight and relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion of ingested food (ECI) , efficiency of conversion of digested food (ECD) , approximate digestibility (AD) and feeding deterrence index (FDI) were calculated. LC50 values in contact, digestive and contact-digestive method were 10.134, 4.940 and 4.612 mg/l, 24 h after application, respectively. However, it was 8.990, 3.791 and 3.622 mg/l at 48 h and 7.898, 2.938 and 2.968 mg/l at 72 h after application, respectively. Arugula oil decreased the nutritional indices containing RCR, RGR, ECI and ECD and increased FDI significantly, 72 h post feeding. These findings indicated post ingestive toxicity of the oil. In general, it could be concluded that arugula oil possessed insecticidal and antifeedant activity against X. luteola. However, further investigations are necessary for commercialization of this product for the agrochemical industries of the natural pesticides.
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