| Pine wood nematode disease, as also known as pine wilt disease, is a kind ofdestructive tree diseases determined by the pine wood nematode (Bursaphelenchusxylophilus) parasiticing in the vivo of Pinus species (Pinus spp.), feeding on thenutrients and resulting in the death of trees. It is hailed as cancer of pine. It has spreadto many countries and regions of the world, and caused serious damage of the nationalforest resources and ecological environment since the discovery of the disease.Currently, the main method to treatment this disease is using chemical nematicides,but this method has the shortcomings of long period, high cost, huge pollution andeasy to produce drug resistance and so on. Therefore, find a kind of efficient, lowtoxicity, environmentally friendly, biological plausibility nematicide has become thehot pot of researches in recent years.Toxicity of ethanol extracts of36traditional Chinese medicinal (TCM) herbs toadult mites and eggs of Bursaphelenchus xylophilus were evaluated in this study inthe view of the abundant plant resources in China. Bioassay results showed that theethanol extracts of Cortex moutan radicis, Coptis chinensis franch and Radix etrhizomarhei possessed excellent efficacy with100%mortality of adults, less than20%egg hatching rate and more than60%mortality of eggs at the concentration of10g/L. The values of LC50were1.81,0.2638and1.07g/L respectively against B.xylophilus after treatment72h. Preliminary separation of active ingredients of threeTCM herbs was used to examine the nematicide activities of the extracts. The activeingredients of C. moutan radicis presented in ethyl acetate extract, while the activeingredients of C. chinensis franch and R. et rhizomarhei presented in water extracts.The values of LC50were0.712,2.370and0.067g/L respectively against B. xylophilusafter treatment72h.The control efficiency of the ethanol extracts of Cortex moutan radicis, Coptischinensis franch and Radix et rhizomarhei against pine wood nematode in greenhousewas tested. The results showed that they all have good control effects. The pinebranchs kept healthy at the concentration of250μg/mL within40days, as the same as the onset of “water+nematode†treatment within10days. But the pines of “water+nematode†treatment began to get disease, and the disease index rase rapidly after10days. In the end, the pines got wilt and even died within40days.Anather objective of this study is to identify the poisoning mechanism of theethanol extracts of three traditional Chinese medicinal (TCM) herbs: Cortex moutanradicis, Coptis chinensis franch and Radix et rhizomarhei. Inhibitory activity of theextracts of three TCM herbs on the mycelia growth of Cordyceps sinensis wasscreened by using the mycelia radial growth inhibition method. The effects of theseextracts were evaluated on the metabolism of total sugar and protein and activities ofprotective enzymes: Superoxide dismutase (SOD), Catalase (CAT), Peroxidase (POD),Glutathione peroxidase (GSH-Px), Acetylcholinesteras (AChE) and the content ofMalondialdehyde (MDA) from Bursaphelenchus xylophilus. Analyzing of the geneexpressive quantity of SOD, CAT, GSH-Px and AChE was made by western blot. Theextracts of three TCM herbs strongly inhibited mycelia growth, interfered themetabolism of sugar and protein of B. xylophilus. The enzyme activities of GSH-Px,CAT, and SOD were improved; the enzyme activity of POD was inhibited. The MDAcontent was increased. Oxidation and antioxidant were imbalance and greatly affectedthe cell functions. The activity of AChE was inhibited, so the nervous system wasdamaged. It is concluded that the changes of some physio-biochemical indexes of B.xylophilus in vivo caused by the extracts of three TCM herbs were the main causes ofits death. |
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