【目的】 爪哇棒束孢Isaria javanica是一种重要的虫生真菌，已广泛应用于多种害虫的防治。本研究从美国白蛾Hyphantria cunea僵虫尸体中分离出对美国白蛾具有致病作用的爪哇棒束孢BE01菌株，为了解该菌株对美国白蛾的侵染过程，并通过研究宿主体内抗氧化酶系对爪哇棒束孢BE01菌株入侵的响应，评价该菌的杀虫作用，为爪哇棒束孢BE01防治美国白蛾提供依据。【方法】 采用扫描电镜技术，观察爪哇棒束孢BE01分生孢子侵染的美国白蛾3龄幼虫，并测定美国白蛾接菌后体内超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）含量的变化。【结果】 爪哇棒束孢对美国白蛾侵染过程包括：分生孢子粘附在美国白蛾的角质层上，接种后6 h孢子开始萌发，24 h产生附着胞，48 h菌丝在体表继续生长，96 h菌丝从虫体内长出并产分身孢子，120 h菌丝覆盖整个虫体。在受到爪哇棒束孢BE01侵染后，美国白蛾幼虫体内的3种抗氧化酶SOD、POD、CAT酶活性明显升高，并在侵染48 h时达到峰值。随着侵染时间的增加，48 h后3种酶的活性开始下降， 60 h后酶活性均低于对照组。【结论】 爪哇棒束孢BE01孢子活力高、萌发速率快，导致美国白蛾体内的保护酶系难以发挥保护作用。爪哇棒束孢BE01菌株能够快速侵染美国白蛾幼虫，具有开发成新的高效生物防治菌株的潜能。

[Objectives]  Isaria javanica is an important entomopathogenic fungi that has been widely used to control various insect pests. The BE01 strain of I. javanica that is pathogenic to Hyphantria cunea was isolated from the surfaces of a cadavers of H. cunea to better understand its insecticidal effect and improve its use as a biological control agent for H. cunea. The process of infection by this strain and the host's associated antioxidant enzyme response were investigated. [Methods]  Scanning electron microscopy was used to observe third-instar H. cunea larvae infected by I. javanica BE01 conidia. Changes in levels of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the bodies of H. cunea after inoculation were measured. [Results]  The infection process had several stages, including adherence of the conidia to the host cuticle, germination of the conidia 6 h after inoculation, development of appressorium after 24 h, hyphal growth on the body surface after 48 h, emergence of mycelium from the body and production of conidia after 96 h, and the entire body being covered by mycelium after 120 h. Activity of three antioxidant enzymes, SOD, POD and CAT, in larvae significantly increased after infection with I. javanica BE01 and peaked 48 h after infection. The activity of all three enzymes began to decrease after 48 h, and were lower than in the control group after 60 h. [Conclusion]  Conidia of I. javanica BE01 have high virulence and a rapid germination rate, which makes it difficult for H. cunea to resist infection. The I. javanica BE01 strain can quickly infect H. cunea larvae, and has the potential to develop into a new, highly effective biological control agent.