Lei Yanyuan, Hussain Abid, Guan Zhaoying, Wang Desen, Jaleel Waqar, Lyu Lihua, He Yurong
Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
Institute of Research and Consultancy, King Faisal University, Hofuf 31982, Saudi Arabia.
Insects. 2021 Feb 18;12(2):179. doi: 10.3390/insects12020179.
The entomopathogenic fungus, is a potential eco-friendly biocontrol agent. The present study revealed the entire course of infection of by with particular reference to cuticular penetration. Comparative studies on the infection of larvae by two strains of with different pathogenicity were carried out using light, scanning, and transmission electron microscopy. We found that tended to adhere to the cuticle surfaces containing protrusions. Although conidia of the lower pathogenic strain IFCF-D58 germinated, they failed to penetrate and complete the development cycle. In contrast, the higher pathogenic strain IFCF01 began to germinate within 4 h and attached to the cuticle by a thin mucilaginous matrix within 8 h post-inoculation. After 24 h post-inoculation, germ tubes and penetrating hyphae reached the cuticular epidermis and began to enter the haemocoel. Within 36 h post-inoculation, the hyphal bodies colonized the body cavity. Hyphae penetrated from inside to outside of the body after 48 h and sporulated the cadavers. After 72 h post-inoculation, numerous conidia emerged and the mycelial covered the entire cuticular surface. The two strains showed similarities in terms of conidial size and germination rate. However, IFCF-D58 exhibited significantly fewer appressoria and longer penetrating hyphae compared to the more infective IFCF01 on all surface topographies. The current pathogen invasion sequence of events suggested that the aggressive growth and propagation along with rapid and massive in vivo production of blastospores facilitate the conidia of IFCF01 to quickly overcome the diamondback moth's defense mechanism.
昆虫病原真菌是一种潜在的生态友好型生物防治剂。本研究揭示了[真菌名称]对[昆虫名称]的整个感染过程，特别关注了其表皮穿透情况。使用光学显微镜、扫描电子显微镜和透射电子显微镜，对两株致病性不同的[真菌名称]感染[昆虫名称]幼虫的情况进行了比较研究。我们发现，[真菌名称]倾向于附着在含有突起的表皮表面。虽然致病性较低的菌株IFCF-D58的分生孢子能够萌发，但它们无法穿透并完成发育周期。相比之下，致病性较高的菌株IFCF01在接种后4小时内开始萌发，并在8小时内通过一层薄的黏液基质附着在表皮上。接种后24小时，芽管和穿透菌丝到达表皮层并开始进入血腔。接种后36小时内，菌丝体在体腔内定殖。48小时后，菌丝从体内穿透到体外并在虫尸上形成孢子。接种后72小时，大量分生孢子出现，菌丝体覆盖了整个表皮表面。两株菌株在分生孢子大小和萌发率方面表现出相似性。然而，在所有表面形貌上，与更具感染力的IFCF01相比，IFCF-D58形成的附着胞明显更少，穿透菌丝更长。目前病原体入侵的事件序列表明，IFCF01分生孢子的快速生长和繁殖以及体内大量快速产生芽生孢子，有助于其迅速克服小菜蛾的防御机制。
