【目的】研究一种自制新型复配杀线虫剂3%(质量分数,下同)氟吡菌酰胺-5%甲维盐微乳剂,探究其对松材线虫(Bursaphelenchus xylophilus)的毒力活性及其在防治松材线虫病方面的潜力,为研发出更加高效且具备快速输导能力的药剂提供参考。【方法】采用浸虫法测定这种新型复配微乳剂(3%氟吡菌酰胺-5%甲维盐微乳剂)以及另外两种市售常用药剂(5%甲维盐微乳剂和5%阿维菌素乳油)的杀线效果;以这3种药剂的两种亚致死浓度(LC₁₀和LC₃₀)处理松材线虫来检测其对线虫繁殖能力的抑制效果;在林间将这3种药剂进行树干注射,观察药剂的可吸收性,以及被树体成功吸收药剂对马尾松造成的敏感性状况;在注药90 d后采集注干松树的枝干样本,检测分析药剂在树体内的输导分布动态;并在注药后100 d对处理马尾松进行人工接种松材线虫,观察统计各药剂对松材线虫病的防治效果。【结果】3%氟吡菌酰胺-5%甲维盐自配微乳剂、5%甲维盐微乳剂、5%阿维菌素乳油处理松材线虫24 h后,测定的致死中浓度(LC₅₀)数值分别为2.644 0、27.678 4、42.891 1 mg/L。3 种供试药剂中,3%氟吡菌酰胺-5%甲维盐微乳剂的杀线能力最强,并且经过低浓度药剂处理过的松材线虫的种群繁殖数量均显著低于对照组。3种药剂注干7 d后,自制复配药剂和5%阿维菌素乳油能够被树体完全吸收,5%甲维盐微乳剂难以被吸收。各药剂注射180 d后,自制复配药剂对树体造成的敏感性情况轻微,注药点的木质部产生轻微的变色情况,5%阿维菌素乳油对树体造成的敏感性严重,注药点的木质部产生了严重的变色情况。在注药90 d后,在树体顶部能够检测到所有药剂的残留。在注干点以下0.5 m位置,复配3%氟吡菌酰胺-5%甲维盐微乳剂中氟吡菌酰胺残留含量(质量分数,下同)达到最高,为0.13 mg/kg,甲维盐残留含量0.07 mg/kg,5%阿维菌素残留含量0.1 mg/kg。2种药剂残留含量均在注干点以上0.5 m位置达到最高,此部位复配药剂中的氟吡菌酰胺的残留含量为55.65 mg/kg,残留含量显著高于其余药物。并且从整体看,复配药剂中的氟吡菌酰胺在树体内的残留含量高于甲维盐的残留含量以及5%阿维菌素乳油。于当年7月中旬接种松材线虫,在接种270 d后注射过药剂的马尾松均保持健康,而未经药剂处理的马尾松在接种后100 d出现感染迹象,表明所有药剂都能有效预防松材线虫病的发生。【结论】毒力效果分析表明,新型自制复配药剂对松材线虫具有较强的毒力作用,在林间对马尾松进行注射后,其可吸收性良好,马尾松对其敏感性轻微,并且在松树体内有良好的输导效果。同时,能够预防松材线虫的感染,具备良好的防效,可继续开展配方的优化以及林间的大面积应用。

【Objective】Injecting agents into pine trees to prevent pine wilt disease is an effective control measure. This study aimed to develop more efficient and fast-delivery agents by combining two different drugs to create a novel microemulsion. The virulence activity of this combined (3% fluopyram-5% emamectin benzoate) microemulsion against Bursaphelenchus xylophilus and its potential for controlling pine wilt disease were explored.【Method】The nematocidal effects of the newly developed combined microemulsion, along with two commonly used agents for pine wilt disease-5% emamectin benzoate microemulsion and 5% avermectin emulsifiable concentrate-were assessed using the insect immersion method. B. xylophilus was treated with lethal concentrations (LC₁₀ and LC₃₀) of each agent to determine their impact on nematode reproduction. Three agents were injected into the trunks of Pinus massoniana trees in the forest to observe agent absorption and tree sensitivity to successfully absorbed agents. After 90 days of injection, samples of the treated trees were collected to analyze the dynamic distribution of drug transport within the tree body. Additionally, 100 days after inoculation, the treated trees were artificially inoculated with B. xylophilus to observe and statistically analyze the control effects of each agent on pine wilt disease.【Result】The LC₅₀ values after 24 hours of treatment with the 3% fluopyram-5% emamectin benzoate microemulsion, 5% emamectin benzoate microemulsion, and 5% avermectin emulsifiable concentrate on pine wood nematodes were 2.644 0, 27.678 4, and 42.891 1 mg/L, respectively. Among the tested agents, the 3% fluopyram-5% emamectin benzoate microemulsion exhibited the strongest nematocidal activity. The population reproduction of nematodes treated with low concentrations of the agents was significantly lower than the control group. Seven days after injection, both the self-made combined microemulsion and 5% avermectin emulsifiable concentrate were fully absorbed by the tree, whereas absorption of the 5% emamectin benzoate microemulsion was more limited. After 180 days, the self-made combined microemulsion showed minimal sensitivity to the tree, with slight discoloration at the injection point, while the 5% avermectin emulsifiable concentrate caused significant discoloration of the xylem at the injection site. After 90 days, residual concentrations of all agents were detected at the top of the tree. The highest residual concentration of fluopyram (0.13 mg/kg) was found 0.5 m below the injection point in the combined 3% fluopyram-5% emamectin benzoate microemulsion, while emamectin benzoate had a residual concentration of 0.07 mg/kg, and 5% avermectin's residual concent ration had 0.1 mg/kg. The highest residual concentrations of all agents were observed 0.5 m above the injection point, with fluopyram in the combined microemulsion reaching 55.65 mg/kg, significantly higher than the other agents. Overall, the residual concentration of fluopyram was higher than that of emamectin benzoate in the combined microemulsion and higher than 5% avermectin emulsifiable concentrate. Inoculation with pine wood nematodes in mid-July showed that, 270 days after inoculation, the trees treated with the agents remained healthy, while untreated trees exhibited signs of infection 100 days post-inoculation. All agents effectively prevented the onset of pine wilt disease.【Conclusion】The toxicity analysis of the new self-made combined agent demonstrates its strong nematocidal effect, good absorbability after injection into P. massoniana, and mild sensitivity to the tree. It also exhibits excellent transport ability within the tree and provides effective prevention against pine wood nematode infection. Further optimization of the formula and large-scale application in forest management is recommended.