Document Type : Research Paper
Authors
1
Ph.D. student, Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
2
Prof. Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
3
Assistant Prof., Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
4
Associate Prof., Research institute of Plant Protection, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
5
Prof., Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
10.22092/ijfrpr.2024.362690.1587
Abstract
Background and objectives: The red flour beetle (Tribolium castaneum (Herbst)) (Tenebrionidae) is one of the main pests of stored products, especially cereal crops, all over the world. In recent years, to reduce the use of chemical pesticides, plant essential oils have gained attention. But despite their good potential, essential oils are unstable, and their toxicity decreases in a short time after use. Nanocapsule formulations can improve the efficiency of plant essential oils on stored product pests by increasing their toxicity and durability. This study was carried out with the aim of preparing nanocapsule formulations of essential oils of Eucalyptus camaldulensis Dehnh. and Eucalyptus globulus Labill. and comparing their fumigant toxicity effects and non-formulated essential oils on T. castaneum adults.
Methodology: Eucalyptus leaves were collected from the Zaghmarz Eucalyptus research station in the south of Behshahr city, Mazandran Province, in July 2018. The collected dried leaves of Eucalyptus were hydrodistilled using a Clevenger-type apparatus. Identification of the constituents of essential oils was performed using GC-MS. Sodium alginate nanocapsules were prepared using basic hydrophilic surfactants. The survey of the surface and wall morphology of nanocapsules was conducted using a transmission electron microscope. The particle size distribution of nanocapsules was also determined. Fumigant toxicity testing was performed separately for each essential oil and nano-capsulated essential oil in four concentrations and at 24, 48, and 72 hours after applying the treatments, along with the control at 25°C and a relative humidity of 65% in darkness. PoloPlus software was used to estimate the LC10, LC25, LC50, and LC95.
Results: According to the results, the number of compounds in the essential oils of E. globulus was higher. The most important compounds of the essential oils of the two Eucalyptus species were terpenes, and 1,8-cineole, limonene, and pinene-α were the most important terpenes in the essential oils of E. globulus and E. camaldulensis, respectively. The results obtained from the transmission electron microscope images showed that nanocapsules containing Eucalyptus essential oil have nanoscale dimensions. The average particle size distribution for E. globulus and E. camaldulensis essential oil nanocapsules was determined to be about 150 and 100 nm, respectively. The essential oil of E. globulus was more toxic than the essential oil of E. camaldulensis. The values of LC50 at 24, 48, and 72 hours after treatment for essential oil nanocapsules of E. globulus and E. camaldulensis were 5.9, 4.63, 3.8, and 9.5, 8.67, 6.7, respectively, and LC50 for raw essential oils of E. globulus and E. camaldulensis were 10.93, 9.63, 5.7, and 15.09, 12.86, 8.2 ml per liter of air, respectively. Based on the results, the nanocapsule formulation of the essential oils of both species, compared to the raw essential oil, showed a decrease in LC50, and the durability of the encapsulated essential oil also increased.
Conclusion: Based on our results, nanoencapsulation of Eucalyptus essential oil increased the fumigant toxicity of the essential oils by enhancing toxicity and the controlled release of effective compounds in controlling this pest. Therefore, this nanocapsule formulation is recommended for further toxicity tests and eventually its use in storage.
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