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چکیده
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Essential oil from Mentha longifolia was extracted by Clevenger - type water distillation, and analyzed using gas chromatography - mass spectrometry. Nano hollow silica spheres were synthesized by sol - gel method as a Mentha longifolia essential oil carrier, and functionalized with thiol groups. The success of Mentha longifolia essential oil encapsulation was clarified by Fourier transform infrared (FT - IR) spectroscopy, Energy Dispersive X - ray Microanalysis (EDX), ult raviolet - visible (UV - vis) spectrophotometry, thermal gravimetry analysis (TGA), and X - ray diffraction (XRD) techniques. In addition, the shape and size of the particles have been determined by scanning electron microscopy (SEM) and transmission electron mi croscopy (TEM). The Fumigant toxicity of Mentha longifolia free and nanoencapsulated essential oils on second instar Tuta absoluta larvae and eggs under laboratory conditions of 25 ± 1 °C and 70 ± 10% R.H. and a photoperiod of 16:8 h (L:D) were investigated. Each treatmen t which consisted of five concentrations and a control was replicated at least six times with 20 - 25 larvae (or eggs ) per replicate. Probit option of SPSS was used for analyzing concentration - mortality data and estimating lethal concentrations. Mortality was corrected based on control mortality using Abbott’s formula. If control mortality was more than 20%, the results were discarded and the bioassay was repeated. LC50 values of Mentha longifolia free essential oil on second instar Tuta absoluta larvae and eggs under laboratory conditions were 3.793, and 6.172 μ L L - 1 air after 24 h, respectively. Furthermore, LC50 values of the fumigant test of nanoencapsulated essential oil on second instar Tuta absoluta larvae and eggs under laboratory conditions were 1.68 and 3.679 μ L L - 1 air after 24h, respectively. LC 50 values were judged as significantly different, if their 95% conf idence intervals did not overlap
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