اثر دورکنندگی سه اسانس گیاهی علیه حشرات بالغ Rhyzopertha dominica (F.) (Col.: Bostrichidae)

The use of pesticides have adverse effects on non-target organisms, toxicity to humans and other mammals, and incidence the development of insect resistance, environmental contamination and etc. Application of botanical insecticides has received increased attention as an alternative to synthetic chemical; insecticides. Lesser gran borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) is one of the serious pests of stored grains. In this study, essential oil of Ferula assa foetida (L.) (assa-foetida) gum, Pelargonium hortorum LH Bailey (geranium) and Juglans regia (F.) (walnut) leaves were extracted and repellent effects of the oils were evaluated using olfactory system. Three concentrations of each essential oil were selected according to the preliminary test. The concentrations were 2.24, 3.45 and 8.80 µL/L acetone for asafoetida oil. For geranium oil, 26.45, 48.54 and 151.0 µL/L acetone and 9.60, 15.54 and 36.22 µL/L acetone in the case of walnut leaf essential oil. Wheat kernels (10 g) were treated with the concentrations and acetone treated wheat was applied as a control. The experiments were carried out at 28±1˚C and 65±5% RH in continuous darkness. This experiment was replicated 10 times, and one adult was used for each replication. Repellency percentage were subjected to one-way analysis of variances and Tukey-Kramer test was used to determine significant differences using SPSS Software version 16.0 at P = 0.05. The results showed that all three essential oils were used in the experiment have repellency properties against adults of R. dominica and the repellency percentage was increased with increasing concentration level. The highest repellency was recorded for assa-foetida, and 2.4, 3.45 and 8.8 µL/L air of the essential oil caused 62, 80 and 100% repellency on adults, respectively. However, 26.45, 48.54 and 151.0 µL/L acetone concentrations of geranium oil caused 12, 35 and 50% repellency on R. dominica. The repellence percentage was 30, 54 and 72% for 9.6, 15.54 and 36.22 µL/L acetone concentrations of walnut oil. According to the results of this research, it can be concluded that assa-foetida essential oil has a greater potential for production and use as an insecticide, although further studies on this essential oil should be performed.