| Melaleuca bracteata is a kind of color-leaf plants which is belongs to Myrtaceae,Melaleuca.Melaleuca bracteata has highly ornamental value,strong stress resistance and its leaves are full of strong flavors which have effect on medical care,healthcare,insecticidal activity,fungicidal activity and antioxidant.The Melaleuca bracteata essential oil(MBEO)was extracted from its leaf in this paper.It had been done that optimizated the enzyme assisted extraction process of MBEO,tested the attractive activity of Bactrocera dorsalis of MBEO and its composites,prepared and characterized the microcapsule with β-cyclodextrin(β-CD)of MBEO and composite essential oil(CEO),prepared and evaluated the suspension concentrate(SC)of CEO/β-CD.The findings from this study would provide a new kind of environment slow-release attractant at controlling Bactrocera dorsalis.The main study results were as follows:1 Enzyme assisted extraction of MBEOResponse surface methodology(RSM)was employed for the optimization of enzyme assisted extraction of MBEO.The optimum conditions were:hydrolysis time,2.9h;hydrolysis temperature,58℃;enzyme dosage,0.52%;and pH,3.83,which yield of oil extraction was 1.39%.The main factors affecting the oil extraction rate were as follows:enzyme dosage>hydrolysis temperature>pH value>hydrolysis time.By gas chromatography-mass spectrometry(GC-MS)analysis,the MBEO detected 21 kinds of volatile compositions extracted by enzyme assisted extraction.The main ingredient was methyl eugenol,the relative content of 81.48%,followed by methyl cinnamate(4.34%),3,4,5-methoxybenzoate(4.26%).2 Study on the attractive activity of the MBEO and its composites to Bactrocera dorsalisThe attractive activity of the MBEO and its composites to the male and female of Bactrocera dorsalis had been tested by Y-type olfactometer in different days age.The results showed that the average attractant rate of undiluted MBEO was higher than methyl eugenol(ME)to male especially it had a strong attractive effect on the male adult in immature period,while it had no attractive effect on the female adult Bactrocera dorsalis;In the compound liquid of MBEO with different combinations and proportions,the sample that had better attractive effected on the male and female of Bactrocera dorsalis in three periods was:MBEO:lemon essential oil(LEO):25%peptone water solution=1:1:2.3 Preparation of MBEO/β-CD and CEO/β-CDWith β-CD as wall material,the microcapsules of MBEO and CEO were prepared respectively by saturated water solution method.Through optimization experiment of the single factor and RSM,the optimum prepared conditions of MBEO/β-CD were obtained:a core wall ration of 12:88(g:g),an embedding temperature at 57℃,an embedding time of 2.5 h;resulting embedding rate and oil content were 68.19%and 10.74%,respectively.The main factors affecting the embedding rate of MBEO were as follows:embedding temperature>core wall ration>embedding time.The main factors affecting the size of MBEO oil content were as follows:core wall ration>embedding temperature>embedding time.The optimal technological conditions for the preparation cf CEO/β-CD were:a core wall ration of 10:90(g:g),an embedding temperature at 49℃,an embedding time of 1.9 h;resulting embedding rate and oil content were 70.70%and 6.75%,respectively.The main factors that affecting the embedding rate of the CEO were in turn as core wall ration>embedding temperature>embedding time.The main factors affecting the oil content of the CEO were in turn as core wall ration>embedding time>embedding temperature.4 Study on structural characterization and release properties of the essential oil microcapsulesBy optical microscopy,scanning electron microscopy(SEM),thin layer chromatography(TLC),UV-visible spectrophotometer(UV-Vis),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and other means,the formation of MBEO/β-CD and CEO/β-CD were verified,respectively.The release properties of the MBEO/β-CD and CEO/β-CD that had been treated with the dark,sealed and exposure were determined respectively under natural conditions by UV spectrophotometry.The results showed that the MBEO/β-CD and CEO/β-CD both presented a slow release trend after 30d.5 Preparation and determination indexes of CEO/β-CD SCBy screening agents(wetting dispersants,thickeners and antifreeze agents),the best formula of CEO/β-CD SC was obtained:the wetting dispersant was 0.5%sodium dodecyl sulfate(SDS)and 3.5%polyvinyl pyrrolidone(PVP),0.1%of the thickener was xanthan gum,1.0%of the antifreeze agent was urea,1.0%of the preservative was sodium benzoate.The performance indexes of SC were determined,such as the active ingredient content,density,suspension rate,dumping,dispersion,thermal storage stability and release rate.6 Efficacy evaluation of CEO/β-CD SC in the laboratoryThe efficacy of CEO/β-CD SC was evaluated by Y-type olfactometer.Compared with other commercially available products and evaluated the different dilutions of the SC to Bactrocera dorsalis.The results showed that:the attractant effect of the SC better than protein bait for male,while the attractant effect of female was not significant;the attractant effect of microcapsules original drug was significantly higher than fruit fly trapping granules for male and female Bactrocera dorsalis.Diluted 2 to 4 times of the SC only had a significant effect for sexual maturity of male Bactrocera dorsalis,and for sexually immature of female only the 2-fold diluted SC had a significant effect. |
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