Frozen section and electron microscopy studies of the infection of the red palm weevil, (coleoptera:curculionidae) by the entomopathogenic fungus .

This study determined the pathogenicity of strain SD-3 against invasive red palm weevil (RPW), Olivier (coleoptera:curculionidae) larvae in Hainan Province, China. Inoculation of 1 × 10 conidia/mL caused 100 % mortality of , indicating that the conidia of strain SD-3 were highly virulent. The process of invasion mechanism was showed by scanning electron microscopy (SEM) and frozen section as follows. Once was infected by strain SD-3, hyphae first invaded the cuticular and body cavity of . Secondly, well-developed muscles, fat, tracheaes and digestive tube tissues in the abdomen of were then decomposed and absorbed by hyphae, leading to the total destruction of the larvae. Finally, hyphae reproduced, resulting in a large number of conidia in the body of RPW. The SEM and frozen section are convenient tools to observe the mode of action of entomopathogenic fungi and to observe how is able to colonize and infect the host.