Document Type : Research Paper

Authors

• Javad Molavi Nafechi ¹
• Faezeh Bagheri ²
• Mohammad Ali Akrami ³
• Fatemeh Raouf Fard ⁴

¹ Department of Plant Protection, School of Agriculture, Shiraz University, Shiraz, Iran

² Department of Plant Protection, School of Agriculture, Shiraz University, Shiraz, Iran.

³ Department of Plant Protection, school of agriculture, Shiraz University, Shiraz, Iran

⁴ Department of Horticultural Sciences, School of Agriculture, Shiraz University, Shiraz, Iran

Abstract

Keywords

• Bioassay
• Inhalation toxicity
• mixture application
• essential oil
• antagonistic effect

Extended Abstract

Introduction

  The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most damaging agricultural pests worldwide. In addition to feeding on plant cells and causing plant weakness, this pest also disrupts transpiration and photosynthesis by weaving webs. Considering the limited number of pesticides for pest control, the emergence of resistance to existing pesticides, and the dangers of using chemical pesticides for non-target organisms and the environment, there is a need to introduce alternatives of natural origin and low risk instead of common synthetic pesticides that leave less dangerous residues in the environment and at the same time have acceptable activity compared to chemical pesticides.

Materials and Methods

the present study investigated the inhalation toxicity of essential oils from two species of Angouze (Ferula assafoetida and F. persica) and one species of Golder (Otostegia persica) against two-spotted spider mites at a temperature of 30 ± 1 °C, relative humidity of 50± 5 %, photoperiod of 16 h of light and 8 h of darkness as a single application, an equal proportion of the mixture of two types of Angouze, and an equal ratio of two kinds of Angouze and one type of Golder. For the experiment, several adult mites of the same age were placed on the leaf discs of the pinto bean plant and placed on a water agar medium. The concentration series used for the bioassay with F.assafoetida, F. persica, and O. persica species included 0, 50, 75, 150, 250, and 300 µL per liter; 0, 17, 35, 50, 70, and 80 µL per liter; and 0, 400, 7000, 15000, 20000, and 25000 µL per liter. Each experiment was performed at six different concentrations, with three replicates for each concentration. Twenty adult mites of the same age (24 h) were used in the present study. A total of 360 one-day-old adult female mites and 1800 mites were used in all bioassays. The experiment was conducted using a completely randomized design in Petri dishes with a diameter of 6 cm using the inhalation method.

Results and Discussion

The results of this study showed that the LC₅₀ values ​​for the essential oils of F. persica, F. assafoetida, and O. persica, a binary mixture of two species of Angouza, and a ternary mixture of essential oils of two species of Angouze and Golder, were 0.054 and 0.2, respectively. It was 0.407, 0.17, and 0.93 microliters per liter of air. The comparison of 50% lethal concentrations of essential oils and their mixtures at the 95% probability level showed that F. persica essential oil has significantly higher smoking properties than other essential oils and their mixtures, and toxicity The mixtures were significantly less than the toxicity of each of the essential oils alone, and based on the comparisons, it was determined that there is an antagonistic relationship between them; Therefore, the best-recommended combination among the studied combinations is F. persica species. Also, this study showed that the essential oils of the two species of Angoze separately have a good acaricidal effect and work much better than the essential oil of Golder. In addition, among these two species, the F.persica species has a greater acaricidal effect than F.assafoetida, and, with its low 50% lethal concentration, it can be a suitable combination for use in the field with additional research. Although the F.assafoetida species can conduct applied research to control this important pest, the F.persica essential oil is more effective and suitable when choosing between these two essential oils. The binary and triple mixing of these essential oils not only does not increase the insecticidal power of the mixture but also causes an antagonistic effect, therefore, mixing these essential oils should be avoided.

Conclusion

In conclusion, the findings emphasize the critical role of essential oil composition in determining acaricidal efficacy. While F. persica emerges as the most effective essential oil in this study, the antagonistic interactions observed in mixtures call for careful consideration in formulation and application strategies. The results contribute valuable insights into the development of sustainable pest management solutions, reinforcing the potential of plant-derived pesticides in addressing the global challenge of pest control.