Fumigant toxicity of three essential oils and methyl iodide on biological parameters of Phthorimaea operculella Zeller) Lep.: Gelechiidae)

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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران

¹Department of Plant Protection Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran

²Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran,,

³Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran

⁴Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil,

⁵Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil,,

The potato tuber worm, Phthorimaea operculella (Zeller), is a major economic pest of potato, Solanum tuberosum L., in both field and stores. In this research, the fumigant toxicity of Thymus caucasicus L., Rosmarinus officinalis L. and Satureja hortensis L. (all from Lamiaceae family) essential oils and methyl iodide (a chemical fumigant) were evaluated on P. operculella demographic parameters at 26 ± 1 ºC, 60 ± 5% RH and 10:14 (L: D) h. Essential oils were extracted by hydro-distillation method using a Clevenger-type apparatus. The gas chromatography / mass spectroscopy (GC-MS) analysis indicated that thymol (29.76%), carvacrol (36.67%) and 1,8-cineole (26.94%) are the major secondary biochemical constituents of the studied plants essential oils, respectively. Fumigant bioassay trials were carried out using a technique developed by Rahman and Schimdt. The ranges of concentrations for different compounds were determined by preliminary dose setting experiments. Twenty one-day old eggs of P. operculella were placed into 250 ml glass vial. Then filter papers of 4 cm in diameter were impregnated with the required doses of essential oils and placed inside the caps of glass vials and covered with Parafilm. The bioassay results showed that LC50 values for T. caucasicus, R. officinalis and S. hortensis essential oils and methyl iodide were 6.20, 4.88, 3.88 and 0.31 μl / L air, respectively. Methyl iodide showed the highest acute toxicity on the egg stage of P. operculella compared to essential oils. The sublethal LC30 doses of essential oils and methyl iodide were 4.48, 3.96, 1.76 and 0.22 μl / L air, respectively. The LC30 doses of essential oils and methyl iodide significantly affected the life history and demographical parameters of P. operculella. The shortest development time was observed in T. caucasicus (18.55 ± 0.11 days) and S. hortensis (18.91 ± 0.15 days) essential oil treatments and the longest was in methyl iodide treatment (24.61 ± 0.20 days). The r values obtained in control, T. caucasicus, S. hortensis, R. officinalis essential oils and methyl iodide treatments were calculated as 0.19, 0.16, 0.14, 0.13 and 0.01 per day, respectively. These results suggested that fumes of methyl iodide and essential oils of all three mentioned plants could be used for potato tuber worm control in storage facilities.

Plant essential oils؛ Methyl iodide؛ Fumigant toxicity؛ Potato tuber worm