A Study On Acaricidal Activity Of Fagraea Ceilanica Thunb

In this thesis, so as to determine the acaricidal parts of Fagraea ceilanica Thunb, plants collected from Guangxi Guilin were used as the research objects, the active ingredients were extracted by organic solvent extraction method, the insecticidal activities of different parts of Fagraea ceilanica Thunb’s extracts to Panonychus citri McGregor were determined by leaf-residue method and Spray method in laboratory. And then to separate and purify the active components, liquid-liquid extraction, silica gel column chromatography and more other separate and purify techniques were used. The chemical structure of active components was identified by spectral analysis techniques. In this thesis, we studied the influence of acaricidal active ingredients to biological activities of Panonychus citri McGregor, protein content, activities of two detoxification enzymes and three protective enzymes in Panonychus citri McGregor female adults, and preliminarily explored the acaricidal mechanism of active componentsUsing leaf dipping method and spray method, the the contact toxicity of Fagraea ceilanica Thunb’s branches and leaves methanol extracts to Panonychus citri McGregor female adults were determined respectivelyThe results showed that their LC50with leaf-residue method were3.4298g/L,4.9236g/L, and LC50with Spray method were3.9682g/L,5.5334g/L. Results of these two methods also showed that all the two plant extracts had good acaricidal activities. Two plant extracts were extracted successively with petroleum ether, ethyl acetate, n-butanol and water, and acaricidal activities of these eight extracts layers were determined by leaf-residue method and Spray method. The two methods resulted in the same results:the petroleum ether layer of branches and the water layer of leaves did well in acaricidal activities. This two extracts layers’48h corrected mortality to Panonychus citri McGregor were85.11%、90.8%in concentration of2.5g/L by leaf-residue method And the results with Spray method were1.7372g/L、3.2970g/L respectively. Also these two active extract layers had repellency and oviposition deterrent activities, the highest repellency rates was80.95%,and the highest oviposition deterrent rate was95.45%.The two active extract layers were isolated by TLC and silica gel column chromatography and then identified as Neriifolin by NMR and MS. Contact poisoning of this Neriifolin to Panonychus citri McGregor female adults, the nymph, the Larva and eggs, repellent activity and oviposition deterring activity were all determined by Spray method in laboratory. Their LC50were1.5742g/L,1.9888g/L,1.4493g/L and2.4618g/L, Respectively. Oviposition deterrent rate of Active compounds was95.34%in concentration of2g/L.The mechanism of Fagraea ceilanica Thunb acaricidal activity substances were preliminarily studied. After treated by contact, Panonychus citri McGregor female adults changeed in body wall appearance:surface water loss, mites shrinking, worms changed black. After extract treatment, insect protein content first decreased and then increased. Fagraea ceilanica Thunb extract could inhibit acetylcholinesterase, superoxide dismutase (SOD), peroxidase (POD) activity, increase catalase (CAT) activity and make the glutathione S-transferase increase at first and then decrease. This phenomenon showed that acetylcholinesterase, superoxide dismutase (SOD), peroxidase enzyme (POD) may be the targets of Fagraea ceilanica Thunb acaricidal active substance, and the oxidative stress reaction may associate with its acaricidal mechanism.