Research On Nematicidal Activity And Mechanism Of Harmaline Derivatives

Using the compounds and their derivatives with nematicidal activity in plants to control plant-parasitic nematodes, is currently an important way to control nematode disease. Based on the evidence that harmaline had a significant nematicidal activity, this article aimed at 27 kinds of chemically-synthetic harmaline derivatives, and step-by-step screened one kind of compound with significant nematicidal activity by the following tests:bioassay of Bursaphelenchus xylophilus and Meloidogyne incognita J2; effects on locomotor behavior of Bursaphelenchus xylophilus; the physiological and biochemical effects on Bursaphelenchus xylophilus.The method of immersion was applied to test the bioactivity of 27 kinds of harmaline derivatives on Bursaphelenchus xylophilus and Meloidogyne incognita J2. The results showed that harmaline derivative F3, F7, F9, F12, F14, F16, F19, F21, F23 and F25 had a more or less significant nematicidal activity on Bursaphelenchus xylophilus and Meloidogyne incognita J2. The corrected mortality on Bursaphelenchus xylophilus of compound F3, F9, F14 and F25 after treatment 72 h were 73.92%, 73.26%, 84.97% and75.32%, respectively;the LC50 on Bursaphelenchus xylophilus of compound F3, F9, F14 and F25 after treatment 72 h were 130.600mg/L, 130.697mg/L, 108.660mg/L and129.318mg/L, respectively. The corrected mortality on Meloidogyne incognita J2 of compound F3, F9, F14 and F25 after treatment 72 h were 74.81%, 72.77%, 85.60% and75.72%, respectively. The LC50 on Meloidogyne incognita J2 of compound F3, F9, F14 and F25 after treatment 72 h were 127.223mg/L, 132.460mg/L, 108.659mg/L and 129.516mg/L,respectively. It was demonstrated that the compound F14 had a more significant nematicidal activity.In terms of the effects on locomotor behavior of Bursaphelenchus xylophilus, the results showed that compound F14 can lead to significant defects of both head thrashes and body bends at the concentration of 150mg/L and 200mg/L, and also a significant defect of forward turns at the concentration of 200mg/L. It was demonstrated that compound F14 can lead to a more significant defect of locomotor behavior.When it comes to the physiological and biochemical effects on Bursaphelenchusxylophilus, the results showed that after treated by compound F14 from 6h to 48 h,acetylcholinesterase of Bursaphelenchus xylophilusis was inhibited and subsequently activated, while α-carboxylesterase, β-carboxylesterase and CAT of Bursaphelenchus xylophilus went through a similar process: inhibition—activation—then inhibition again.What’s more, the activity of acetylcholinesterase, α-carboxylesterase, β-carboxylesterase and CAT were all lower than the control level after treatment 48 h. It was demonstrated that to some degree, compound F14 has an inhibitory effect on the acetylcholinesterase,α-carboxylesterase, β-carboxylesterase and CAT of Bursaphelenchus xylophilus.Finally, this article discussed the mechanism of how botanical nematicides control nematodes and studies on the behavioral toxicity of nematodes, and pointed out the problems to be further explored,in order that it can provide some useful references and positive impacts for the development and creation of botanical nematicides with both high efficiency and low toxicity.