Comparative Study Of Structure, Composition And Function Of Silkworm Ecdysis Content And Cicada Slough

For the need of industrial production and Insecticidal hamper in recent years, there are more and more the study about insect cuticle. And there are deep researchs about the component、structure and function of insect cuticle, which are no longer confined to the macro research. As the representative of lepidoptera insects, there is little research of epidermis on silkworm. This study selected the silkworm pupal stage、5th ecdysis content and the common traditional Chinese medicine cicada slough to explore the structure, composition and function. In our study, we observed the skin on the back of the structure of cicada slough、silkworm puparium ecdysis using scanning electron microscopy(SEM) and transmission electron microscopy(TEM); We used n-hexane to soak the powder to extract of composition cicada slough、 silkworm puparium and 5th ecdysis in normal temperature conditions, then used GC-MS technique to analyze the extractive ingredients; Then we analyzed the inorganic element content of three kinds of materials; We used cicada slough 、 silkworm puparium and the shed substance of the 5th instar silkworm larvae as materials to extract and obtain the chitosan,then measured the structures of three chitosans by using infrared spectrum technology, and analized comparatively their characteristic coefficients at the same time; We conducted the oxidation experiments and bacteriostasis experiment of the chitosans obtained from three materials, and analyzed the inhibitory effect on Escherichia coli and Staphylococcus aureu. According to these studies, we mainly got the following results:1、According to the scanning electron microscope, we observed that the cicada slough abdomen on the back of the cascade structure was relatively flat surface, the surface between the internode was relatively smooth, and there were stripes on the section in deep ravines structure, between which were a lot of different particles swelled. The chest back surface of cicasa slough was relatively smooth and there were some particles and surface cracks accompanied by a small amount of uneven size bristles structure. The bristles was short and thin,whose roots were sunk. The surface bristles of silkworm puparium were more intensive than cicada lough, which presented neat polygon mesh structure of wrinkles, and polygon structures were mainly 5-7 angle, chitin and protein formated the structure of complex which formed the polygon skeleton, granular inorganic salt filled in the structure of the polygon plane; The bristles were slender on its outer surface whose roots presented the navel shape and distributed around tiny particles, uplift collar shape around the base of skin. The surface structure of silkworm papurium were different from cicada slough skin surface which was relatively smooth, because there were nadels on the one side and polygons on the other side between somite membranes of papurium. According to the transmission electron microscope, the chest back surface of cicada slough exocuticle was more thick than silkworm puparium, and the endepidermis was relatively flat which presented compact layer structure. While the exocuticle of papurium was more thin, and the layer structure of endepidermis was relatively crooked maybe because of section reason, at the same time, there were many the meatus branchs in endepidermis and the section presented a lot of irregularity and variform drape. The endepidermis of cicada abdominal back was not compact as puparium and exocuticle was thick than puparium. The exocuticle of puparium was thin and close to the endepidermis. There was also a relatively continuous wax layer and cement layer on the surface of epicuticle. Due to processing of the organic solvent in the process of slicing, wax layer and cement layer was partly dissolved. The cicada didn’t have obvious wax layer and cement layer, this may be the wax layer was different from puparium or in the process.2、The three kinds of materials had alkane as main ingredient, relative contents were 86.75%, 91.35% and 74.55%, followed by alcohols esters, little fatty acid. Hexacosane is the main alkane of cicada slough and puparium ecdysis, hentriacontane in the shed substance of the 5th instar silkworm larvae. All three contained tetracosanol、heptacosanol; octadecanoic、methyl palmitate, but their relative content were different. Only puparium ecdysis contained 15-hydroxy pentadecane acid accounting for only 0.22%. According to whether containing branched chain, divided into alkanes and branched alkanes, mainly include straight-chain alkanes, single methyl alkanes, double paraffin, trimethyl of alkanes and tetramethyl paraffin, do not contain olefins, including alkanes majority. Even number can be divided into odd number alkane and in accordance with the carbon chain alkanes, which even the relative content of alkane were significantly higher than that of the relative content of odd number alkane.3、According to the several microelements experimental results of silkworm ecdysis content and cicada slough, several microelements content of puparium ecdysis was high, content of K、Mg were the highest, Na content was center, except the Ca element content was the lowest. And overall content of the shed substance of the 5th instar silkworm larvae was high except the content of K、Mg in the middle, Na and Ca content were the highest. Cicada slough content was the lowest, except the level of the Ca element in the middle. The trace elements amount of cicada slough were Fe>Mn>Zn>Cu, while the puparium ecdysis Zn>Fe>Mn>Cu and the shed substance of the 5th instar silkworm larvae Fe>Zn>Mn>Cu. The difference of microelements summation between cicada slough and silkworm puparium ecdysis was very small, while there was a greater difference between trace elements.The trace elements of puparium ecdysis was the lowest only 321.270 mg/Kg. Ca element content of the shed substance of the 5th instar silkworm larvae was very high, which made the microelements up to 59 321.117 mg/Kg, which was five times than cicada slough and puparium ecdysis as much. And trace elements summation amount of puparium ecdysis was slightly below the cicada slough, but sumamount was still the cicada and pupa shedding 4 times as much.4、The infrared spectroscopy of three chitosan were basically similar to guide sample chitosan, only different from individual peaks, peak positions, showing the basic structure of three chitosan were similar. The viscosity and molecular weight of three kinds of chitosan were different. The viscosity of chitosan prepared from cicada slough was up to 90.4 mPa·s, while that of chitosan prepared from shed substance of the 5th instar silkworm larvae was the lowest(only 11.7 mPa·s). The relative molecular weight of chitosan prepared from puparium and the shed substance of the 5th instar silkworm larvae was 2.6×104 and 1.2×104 respectively, both of which were lower than that of chitosan prepared from cicada slough(1.0×105). The degree of deacetylation of chitosan prepared from cicada slough and puparium was similar, while that of chitosan prepared from the shed substance of the 5th instar silkworm larvae was slightly lower.5 、 The three different sources of chitosan on antioxidant and antibacterial experiments showed that the chitosan’s ability to resist oxidation reduction increased with the increase of the concentration, and the reduction in chitosan prepared from the shed substance of the 5th instar silkworm larvae force was stronger. When determination to take off the oxidation of hydrogen removal ability, the clearance rate of chitosan prepared from cicada slough and puparium were higher, clearance rate of chitosan prepared from the shed substance of the 5th instar silkworm larvae was in a low level. Bacteriostatic experiment results showed that the bacteriostatic effect of different in different pH conditions, three kinds of chitosan antibacterial optimum pH was at pH 4.5 to 6.5. By measuring the size of the bacteriostatic circle, chitosan prepared from the shed substance of the 5th instar silkworm larvae had the strongest antibacterial effect followed by chitosan prepared from cicada slough and puparium.6、The shed substance of the 5th instar silkworm larvae and puparium and cicada slough are excellent raw materials for development of insect chitosan. We extracted the chitosan from these materials against industrial tradition of crayfish materials. Because they had many advantages such as high purity, less impurities, had very good antioxidant and antibacterial effect, and inorganic element content was rich. And they had the very good development and utilization value. In addition, the epidermis GC-MS composition analysis also provided the basis for the classification of the insects.