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Studies On The Growth Regulation Of Azadirachtin In Ostrinia Furnacalis (G.) And Spodoptera Litura (F.)

Posted on:2006-12-29Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z W HuangFull Text:PDF
GTID:1103360152999412Subject:Zoology
Abstract/Summary:PDF Full Text Request
Botanical insecticides are broadly used in insect pest control and environmental protection. Azadirachtin, as a kind of plant protector, induces a wide variety of biological processes, which has been testified in both laboratory and practical application. However, the mode of action of the bioactivities remains obscure, which seriously limit its widespread use. Therefore, it is essential to study its biochemical modes. In the present study, on the basis of its biological activity, we studied its effects on sex pheromone, fatty acid, protein expression and ecdysone titer and so on. The main results were as following: Azadirachtin had remarkable poison and growth inhibition on Ostrinia furnacalis (G.) and Spodoptera litura (F.). Feeding larvae with azadirachtin causes, in a dose-dependent manner, active reducing, pupation delay, and many kinds of abnormal larvae, pupae and adult insects. Furthermore, effects of azadirachtin on sex pheromone synthesis were investigated in Ostrinia furnacalis (G.). The results showed that the sex pheromone titers were significantly decreased in adult survivors with the increase of azadirachtin concentration. There was no difference between control and those treated with 3ppm azadirachtin. The moth sex pheromone titers were significantly decreased and 30% less than control when larvae treated with 5 and 10ppm azadirachtin, the titer reached only 50% when larvae treated with 15ppm azadirachtin. However, there were no obvious effects of azadirachtin on the ratios of sex pheromone components. Sub-lethal effects of azadirachtin on fatty acid in larvae, pupae and adult survivors of Ostrinia furnacalis (G.) were investigated by using GC-MS. The results indicated that the quantities of fatty acid in larvae, pupae and adult survivors were significantly reduced when larvae treated with 0.1-10ppm. After ten days, the quantity treated with 10ppm was only half of control; meanwhile, azadirachtin affected the composition of fatty acid. The relative content of component C18:2 significantly decreased in adult survivors, which suggested the correlation with the reproductive reduction. Protein metabolism was significantly influenced by azadirachtin in Spodoptera litura (F.) and Ostrinia furnacalis (G.). The total soluble protein content was measured and the results showed that protein level treated with azadirachtin were obviously lowered. Moreover, the female present a stronger response to azadirachtin than male in protein synthesis. By using SDS-PAGE and 2-DE (Two-dimensional polyacrylamide gel electrophoresis), we analyzed changes in protein metabolism of 48h pupae and found that there were altogether more than ten proteins up-regulated or down-regulated induced by azadirachtin. The comparison of proteomic analysis in pupae survivors of Spodoptera litura (F.) showed that ten proteins significantly changed between control and treatment with azadirachtin. Six of these proteins were successfully identified with peptide mass fingerprinting using MALDI-TOF-MS after in-gel trypsin digestion, especially one down-regulated is identified as ecdysone receptor; The comparison of proteomic analysis in pupal hemolymph of Ostrinia furnacalis (G.) showed that six proteins significantly changed between control and treatment. Two of these proteins, which were both up-regulated, were successfully identified with peptide mass fingerprinting using MALDI-TOF-MS after in-gel trypsin digestion, respectively belong to the insect apolipophorin-III and the...
Keywords/Search Tags:Azadirachtin, Ostrinia furnacalis, Spodoptera litura, bioactivity, sex pheromone, fatty acid, Proteome, Ecdysteroid (20-E)
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