| Fumigant toxicity of three essential oils and methyl iodide on biological parameters of Phthorimaea operculella (Zeller) (Lep.: Gelechiidae) |
| Paper ID : 1226-3IICE (R1) |
| Authors: |
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Mina Jafari *, Gadir Nouri-Ganbalani, Hooshang Rafee-Dastjerd, Aliasghar Fathi, Mahdi Hassanpour Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran |
| Abstract: |
| The potato tuberworm, Phthorimaea operculella (Zeller), is a major economies 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 and on its demographic parameters under the laboratory conditions: 26 ± 1 ºC, 60 ± 5% RH and photoperiod of 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. 20 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 they were placed inside the caps of glass vials and covered with Parafilm. The bioassay results showed that LC50 values for T. caucasicus, R. officinalis, 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 on T. caucasicus (18.55±0.11 days) and S. hortensis (18.91±0.15 days) essential oils and the longest was on methyl iodide treatment (24.61±0.20 days). The rm values obtained in control, T. caucasicus, S. hortensis, R. officinalis essential oils and methyl iodide 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 tuberworm control in storage facilities. |
| Keywords: |
| Plant essential oils, Methyl iodide, Fumigant toxicity, Potato tuberworm |
| Status : Paper Accepted (Poster Presentation) |
