اثر اسانس و عصاره گیاه کاکوتی روی بید سیب زمینی Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae) در شرایط آزمایشگاهی

Potato tuber moth, Phthorimaea operculella L. is considered to be one of the most serious insect pests infesting family Solanaceae. An alternative method of management of this pest in stores is the use of plants based materials. In this research, lethal effect of Ziziphora tenuior L. essential oil and extract were evaluated on different biological stages of P. operculella in laboratory conditions. Oviposition-preference activity of adults was also studied. All bioassays were performed based on completely randomized design with 5 different concentrations plus witnessed. Experiments were carried in three replicates. Twenty same-age insects were used for each replicate. Glass vials (250 mL) were used for the experiments as fumigant chamber for essential oil. The Whatman filter papers of 3 cm in diameter were impregnated with the required concentration of Z. tenuior essential oil, placed inside the caps of glass vials. Insects (egg, larvae or adults) were put in vials. The caps of glass vials covered with parafilm. In order to investigate the effect of extract on larvae and adults, leaf-dipping method was used. Potato leaflets (6-8 cm diameter) were dipped in the main extract concentrations. After drying in laboratory conditions, they were transferred to 8 cm diameter petri dishes. Some holes were made in the lid of dishes. Twenty one-day-old insects were put into each petri dishes. In the egg trials, filter paper containing 20 eggs were dipped in main concentrations of extract for 15 seconds. After drying, they were placed in plastic petri dishes. Hatching percentage of eggs and mortality of adults and larvae were counted after 7 days, 24 h and 24 h, respectively. Based on Probit analysis, the LC50 values of Z. tenuior essential oil and extract for egg, first larvae and adults were 11.33, 3.09, 0.14 μl L-1 air and 812.61, 155.34, 247.70 ppm, respectively. In investigation oviposition-preferance, three potato tubers were dipped in 1ml of 5% botanical extract or essential oil for 15 seconds and the fourth one (control) was dipped in solvent alone. After solvent evaporating, potato tubers were put in four sides of exposure cage (32*32*32cm). In the essential oil tests, each tuber was placed in a 500 ml container. Ten virgin pairs of one-day old adults were transferred into each exposure cage or container and their oviposition rates were recorded after 72 h. results showed that the pest prefers untreated potatoes for oviposition. The mean of eggs laid on treated tubers with Z. tenuior extract and essential oil were significantly different from the control and were equal to 17/00± 0.01, 26.67± 0.11 and 84.67± 0.58, respectively. According to the results, the use of Z. tenuior essential oil and extract as a botanical insecticide in the management of P. operculella seems promising.