›› 2014, Vol. 57 ›› Issue (4): 418-427.doi:

• 研究论文 • 上一篇    下一篇

金龟子绿僵菌及其粗毒素对樟巢螟幼虫的致病性

童应华, 李万里, 马淑娟   


  1. (福建农林大学林学院,福州 350002)
  • 出版日期:2014-04-20 发布日期:2014-04-20

Pathogenicity of Metarhizium anisopliae and its crude toxin against Orthaga achatina (Lepidoptera: Pyralidae) larvae

TONG Ying-Hua, LI Wan-Li, MA Shu-Juan   

  1. (College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China)
  • Online:2014-04-20 Published:2014-04-20

摘要: 【目的】为了筛选感染樟巢螟Orthaga achatina幼虫的高致病力金龟子绿僵菌Metarhizium anisopliae菌株,并研究绿僵菌粗毒素对幼虫的毒力和取食粗毒素后幼虫的血淋巴细胞免疫反应。【方法】以死亡率时间几率值法和TDM模型分析绿僵菌及其粗毒素对樟巢螟幼虫的致病力,并显微观察处理幼虫的血淋巴细胞的变化。【结果】绿僵菌菌株Ma1291-2对樟巢螟幼虫有较强的致病力,以浓度(1.0±0.5)×108个孢子/mL的孢子悬液接菌11 d后,幼虫的校正死亡率和僵虫率分别为99.8%±2.6%和86.9%±1.3%,LT50为6.29 d。各菌株产粗毒素水平与其对幼虫的校正死亡率和LT50呈显著相关。通过时间-剂量-死亡率模型参数估算,Ma1291-2菌株及其粗毒素对幼虫致死效应较强的时间段分别为接菌后6-7 d和3-4.5 d。幼虫取食绿僵菌粗毒素后2 d,总血细胞、浆血细胞、珠血细胞和类绛血细胞浓度上升到最高值,而后下降;粒血细胞浓度2 d后开始极显著上升,第3天达到最高值后急速下降;原血细胞前3 d未发现有明显的数量变化,第4天显著下降。幼虫取食粗毒素3~4 d后,浆血细胞和粒血细胞有破裂,珠血细胞和类绛血细胞有黑化现象,原血细胞病态变化不明显。【结论】樟巢螟幼虫取食绿僵菌粗毒素后2-3 d,幼虫血淋巴细胞对粗毒素的免疫反应最强烈,且粗毒素对血细胞有毒害和破坏作用。本研究为该害虫的生物防治提供了一定的理论与应用基础。

关键词: 金龟子绿僵菌, 粗毒素, 樟巢螟, 致病性, 血细胞, 免疫反应

Abstract: 【Aim】 The study aimed to screen a highly pathogenic Metarhizium anisopliae strain against Orthaga achatina larvae, to determine its virulence by feeding larvae with crude toxin and to assess the lymphocyte responses in the larvae. 【Methods】 The virulence of M. anisopliae strains and crude toxin to O. achatina larvae was assessed using mortality-time probability method and TDM model, respectively, and the changes of lymphocytes in treated larvae were observed through a microscope. 【Results】 When various strains are compared, Ma1291-2 strain exhibited the strongest virulence against O. achatina larvae, causing a corrected mortality of 99.8%±2.6%, the cadaver rate of 86.9%±1.3% and the half lethal time (LT50) of 6.29 d after inoculation with (1.0±0.5)×108 spores/mL for 11 d. The crude toxin levels produced by different strains were significantly correlated with the corrected mortality and LT50. A time-dose-mortality model was employed to estimate parameters of time and dose, showing that Ma1291-2 strain and its crude toxin had a strong lethal effect on O. achatina larvae during 6-7 and 3-4.5 d after treatment, respectively. The concentrations of total hemocytes, plasmatocytes, spherulocytes and oenocytoids reached the maximum at 2 d after the larvae were fed with the crude toxin of Ma1291-2 strain and then declined. The concentration of granulocytes rapidly increased at 2 d after the larvae were fed with the crude toxin of Ma1291-2 strain, and reached a peak at 3 d after treatment. However, the concentration of prohemocytes did not show any significant change during the first three days of treatment, but decreased significantly at 4 d after treatment. Rupture of plasmatocytes and granulocytes, and melanization of spherulocytes and oenocytoids were observed during 3-4 d after treatment with the crude toxin of Ma1291-2, but prohemocytes did not significantly change. 【Conclusion】 The results show that the immune response of larval lymphocytes to the crude toxin is the strongest during 2-3 d after treatment, and the crude toxin is toxic to lymphocytes. This study proves potential applicability of this pathogen in the development of biological control for O. achatina.

Key words: Metarhizium anisopliae, crude toxin, Orthaga achatina, pathogenicity, hemocyte, immune response