Bioactivity Of The Extract Of The Boenninghausenia Sessilicarpa Against Panonychuscitri And Tetranychus Cinnabarinus And Its Mechanism

Bioactivity of the Extract of the Boenninghausenia sessilicarpa against Panonychus citri and Tetranychus cinnabarinus and Its Mechanism Phytophagous mites were common pests in numerous cropping system.Infestations were often caused by insecticide applications that reduce natural enemy populations or to increase spider mite fertility. The frequent use of pesticides has inevitably resulted in the outbreaks of spider mites.Increasing levels of resistance to the most commonly used acaricides have caused multiple treatments,including overdees,rasing serious environmental and human health concorns. Not only might certain natural products be source of new pesticides, but botanical derivatives may be more environmentally being than synthetic chemicals.The botanical acaricides are trend that new pesticides develope these days. The result the extract of 20 species plant against Panonychus citri suggested that acaricidal activityof the extraction of the Beonninghausenia sessilicarpa L. was the most effective .Acaricidal activityof the extraction of the B sessilicarpa against P citri and Tetranychus cinnabarinus Boisduval was investigated,and its Primary mechanism was investigated through the changes of several enzyme. And the crude extraction was separated by liquid-liquid distribution and purified through gel column chromatograghy. The results indicated:1. The contact activities of ethanol extracts from twenty plants against Panonychus citri were measured in the laboratory with slide dip.The results demonstrated that ethanol extracts of Boenninghausenia sessilicarpa ,Laggera pterodont ,Humulus scanden and Rabdosia had aearicidal activity, of which corrected mortality was above 80% after 24h. The further results indicated that the extraction of ethanol of B. sessilicarpa appeared strong aeadcidal activity, while the LC₅₀ values of egg,nymph and female mite were 1.7062,0.7878 and 0.9241mg.ml^-1, respectively.2. The acarcidal bioaetivities of ethanol, ethyl acetate, chloroform, petroleum ether sequential and parallel extracts from B. sessilicarpa were carried about in this paper. The results showed that at 4mg.ml^-1conentration, treatment after 24h, the corrected mortality of ethanol and ethyl acetate, extract from B. sessilicarpa against P.citri was 94.68%, ethanol, ethyl acecate was 90.99 %,54.19%.3. Three biossays techniques were tested against P. citri:slide dip,spray,and absorption. Slide dip was the most effective method,corrected mortality 92.31% of the crude extract. Absorption was the least effective method,corrected mortality 6.67% of the crude extract. Mite mortality for all three biossays techniques suggested that the extract of B. sessilicarpa mainly possessed contact toxicity to the mite.4. The crude extraction was separated by liquid-liquid distribution.The leach rate of water was the highest (50.66 %).However, ethyl acecate was the lowest(5.79%), and this part appeared a strong acaricidal activity.The LC₅₀ values of egg,, nymph, female mite were 1.1033mg.ml^-1 ,0.3226mg.ml^-1,0.7639mg.ml^-1 ,respectivelywithP.citr,and 1.013mg.ml^-1, 0.8451mg.ml^-1 ,1.5652mg.ml^-1 with Tetranychus cinnabarinus.5. By column chromatograghy part, the chloroform part was separated by 14 part. And the acaricidal activity of part 2 was the strongest activity. Particularly the LC₅₀ value of part 2 against P.citri and T.cinnabarinus was 0.2662 mg.ml^-1, 0.1897mg.ml^-1.The substance in part 2 need farther investigation.6. Every concentration of the crude had infection of the egg growth of P citri. The higher concentration, the more violence restrain. The result of reproduce ability showed that part 2 had violent infection against the female mite.And the higher concentration, the more violence restrained. Part 2 showed fine oviposit inhibition effect against Panonychus citri, especially the concentration above 2.5 mg.ml^-1 the inhibition rate was 0.8795. But along with concentration decreased, the inhibition rate declined fast, till 0.5 mg.ml^-1, the inhibition action disappeared.7. Primary mechanism indicated: The extract could cause the fast reaction of the enzymes inside the mites. It could stir up to counteract poison such as GSTs ,and Care was restraint, make mites declined poison through ethanol control; but the extract cann't restraint POD.