Evaluation of fumigant toxicity of four plant essential oils against adults of Sitophilus oryzea under laboratory conditions
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Rice weevil, Sitophilus oryzae L., (Coleoptera: Curculionidae) is one the most important pests of stored grains worldwide and causes economic damage. The female chew a hole in whole grain and deposits a single egg within the hole. The larva develops within the grain, hollowing it out while feeding. Fumigant toxicity of four plant essential oils including Mentha piperita L., Satureja hortensis L., Foeniculum vulgare L. and Rosmarinus officinalis L. were evaluated against the adults of rice weevil under laboratory conditions (25±2°C, 65±5% R.H. and 16L: 8D h). The essential oils were obtained by hydro distillation using a Clevenger apparatus. Bioassays were done in 27 ml glass vials on one week aged adults. Treatments were carried out with impregnated filter paper method. The mortalities of the treated adults were recorded 24 hours after treatment. Polo PC software was used for calculating LC50 and LC90. All essential oils showed high fumigant toxicity against S. oryzae adults. The results indicated that mortality of adults increased with increasing essential oil concentration. Among the oils, S. hortensis showed to have highest toxicity with the lc50 value of 25.79 µl l-1 air. The LC50 values for M. piperita, F. vulgare and R. officinalis were 86.81, 107.81 and 54.19 µl l-1 air, respectively. Results of this study showed that all tested essential oils, especially S. hortensis, could act as a plant protectant against rice weevil.
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