短稳杆菌对茶尺蠖中肠细胞形态与血淋巴解毒酶的影响

Effects of Empedobacter brevis on midgut cell morphology and hemolymph enzyme activity in Ectropis obliqua Prout(Lepidoptera:Geometridae)

微生物农药短稳杆菌Empedobacter brevis在防治茶园茶尺蠖Ectropis obliqua Prout中得到了广泛的应用,本研究旨在了解该生物农药对茶尺蠖中肠细胞结构及血淋巴酶活性的影响,为日后更好防治该虫提供理论基础。通过毒力测定方法测定了该生物农药对5龄茶尺蠖幼虫的半数致死浓度LC50值,使用透射电子显微镜(TEM)检测了该药对茶尺蠖中肠细胞结构的影响。最后,利用酶标仪检测了该生物农药对茶尺蠖血淋巴解毒酶酶活的影响。药效毒力测定结果表明,短稳杆菌对5龄茶尺蠖幼虫的LC50值为每毫升3.077×105个孢子。透射扫描结果显示,该生物农药具有破坏5龄茶尺蠖幼虫中肠细胞结构及细胞器结构的功能;酶活性检测结果表明,该药对5龄茶尺蠖血淋巴内解毒酶(AchE、CarE和GSTs)的酶活性呈现先升高(12 h)后降低(24 h)的趋势。推测,短稳杆菌对茶尺蠖幼虫的毒杀作用可能与血淋巴解毒酶的活性及中肠细胞结构的破坏有关。

Empedobacter brevis has been widely applied as a microbial agent to control the infestation of Ectropis obliqua Prout(Lepidoptera:Geometridae)on tea bushes at plantations.This study aimed to decipher the mechanisms of the insecticidal function of E.brevis.Changes on the cellular structure of the midgut and hemolymph enzyme activity in E.obliqua after being treated with E.brevis were examined for the analysis.A toxicity assay was used to determine the lethal concentration(LC50)of the microbial agent on the 5th instar larvae of E.obliqua.The effect on the midgut morphology was observed under transmission electron microscopy(TEM).Finally,the hemolymph enzyme activity were detected by the microplate reader.The results showed that the LC50 was 3.077×105 spores/mL,the midgut cell and organelle structures were disrupted,and the hemolymph enzymes significantly affected.The activities of the detoxifying enzymes in 5th instar larvae of E.obliqua,including AchE,CarE and GSTs were increased in 12h,then declines in 24h.It appeared that the death of E.obliqua caused by E.brevis might be related to the altered hemolymph detoxification enzyme activity and the destructed midgut cell structure of the insect.