喜旱莲子草与乌蔹莓等植物提取物对松材线虫的毒杀活性研究

【目的】松材线虫病是当前我国林业生产上危害最严重的森林病害。尽管投入了大量的人力、物力和财力,但松材线虫病防控形势依然严峻。化学杀线剂具有环境局限性,研发高效植物源杀灭松材线虫的药剂对控制松材线虫病疫情,同时降低环境化学污染具有重要意义。【方法】采用乙醇浸渍提取法制备喜旱莲子草(Alternanthera philoxeroides)、乌蔹莓(Cayratia japonica)、迷迭香(Rosmarinus officinalis)等30种植物的提取物,测定其对松材线虫的毒杀活性。利用液液萃取法,用乙醇、石油醚、乙酸乙酯、正丁醇和水等有机溶剂对两种植物中的活性成分进行分步提取,得到药液的质量浓度梯度为10.000、5.000、2.500、1.250和0.625 g/L,并分别测定其对松材线虫的毒杀活性。虫卵悬浮液在25 ℃恒温保湿培养箱内培养,24 h后开始观察,32 h后结束观察。通过镜检统计线虫卵数,并计算相应的线虫卵累计孵化率和孵化抑制率。【结果】采用质量浓度为10 g/L的喜旱莲子草、乌蔹莓乙醇提取物分别处理松材线虫,72 h后线虫校正死亡率均为 100%。喜旱莲子草的乙酸乙酯萃取物和乌蔹莓的水层萃取物中存在主要的杀线活性物质,两种植物萃取物处理松材线虫72 h后的半致死剂量(LC₅₀)分别为0.588 8和0.969 3 g/L。在离体虫卵孵化试验中,喜旱莲子草的乙酸乙酯萃取物对线虫的卵孵化抑制率最大,为79.77%,其次为乌蔹莓的水层萃取物,为46.51%。【结论】可见,喜旱莲子草和乌蔹莓对松材线虫成虫和虫卵均具有较强的生物毒杀活性,可作为新型植物杀线虫剂加以开发利用。

Nematocidal activity of extracts of Alternanthera philoxeroides and Cayratia japonica against Bursaphelenchus xylophilus

【Objective】The pine wilt disease is the most serious forest disease in China. Despite considerable investment in manpower, material and financial resources, the prevention and control situation of the pine wilt disease continues to be a serious issue. Due to the limitations of the large-scale application of chemical nematicides, developing high efficiency botanical nematicides to control the pine wilt disease epidemic will be of great importance. 【Method】 The extracts of 30 plants including Alternanthera philoxeroides, Cayratia japonica and Rosmarinus officinalis were prepared using the ethanol impregnation method; their poisonous activity to the pine wilt disease was then determined. Petroleum ether, ethyl acetate, n-butanol and water were used to extract the active ingredients from two plants via the liquid-liquid extraction method. The concentrations of the solutions were 10.000, 5.000, 2.500, 1.250 and 0.625 g/L, respectively, and insecticidal activities against pine wood nematodes (Bursaphelenchus xylophilus) were determined. The egg suspension was cultured in a constant temperature and moisture incubator at 25 ℃, and observation began after 24 h and ended after 32 h. Microscopic examination was used to count the number of nematode eggs, and the corresponding cumulative hatching and hatching inhibition rates of nematode eggs were calculated. 【Result】 (1) The pine wood nematode was treated with ethanol extracts of A. philoxeroides and C. japonica at a mass concentration of 10 g/L; after 72 h, the corrected mortality of nematodes was 100%. (2) The ethyl acetate extract of A. philoxeroides and the aqueous extract of C. japonica were the key nematocidal substances. The Lethal Concentration 50 (LC₅₀) of pine wood nematodes was 0.588 8 and 0.969 3 g/L after 72 h of the treatment. (3) The in vitro egg incubation test demonstrated that the extract from A. philoxeroides in ethyl acetate exhibited the greatest rate of nematode incubation inhibition of 79.77%, followed by the aqueous extract from C. japonica which had an incubation inhibition rate of 46.51%. 【Conclusion】 A. philoxeroides and C. japonica demonstrated the strong inhibitory biological activity for nematode adults and eggs, which may be developed and utilized as new nematicides for plants.