Electron microscopic observation of infection of Adelphocoris suturalis by Beauveria bassiana
Author of the article:ZHANG Xiao LIU Jia YANG Yi-Hua WU Shu-Wen
Author's Workplace:College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
Key Words:Beauveria bassiana; Adelphocoris suturalis; scanning electron microscopy; transmission electron microscopy; infection process
Abstract:
[Objectives] To reveal the pathogenic mechanism of infection of Beauveria bassiana and investigate the effectiveness of B. bassiana as a biological control for mirid bugs. [Methods] The process of
infection of Adelphocoris suturalis by the Bb-VIII strain of B.
bassiana was observed with both scanning and transmission electron
microscopy. [Results] At the beginning of inoculation, B.
bassiana adhered to epidermal folds, depressions and body joints of A.
suturalis. After 16 h germinated conidia formed germ tubes that invaded the
cuticle of A. suturalis with the aid of extracellular hydrolyzing enzymes and
mechanical stress. After 36-72 h hyphal bodies had invaded muscle tissue, the
fat body, intestinal villi, proliferating in
the body cavity by both septation and budding. Finally, after 48 h hyphae
emerged from the cuticle and developed into aerial hyphae
and conidia. The cuticle of dead A. suturalis was completely covered by
hyphae. [Conclusion] Attachment of B. bassiana conidia
is affected by structural features of the body wall of A. suturalis. The
infection process was completed within 48 h of inoculation, which shows that B.
bassiana is highly pathogenic to A. suturalis. The mechanism by
which hyphae invade the host cuticle involves not only mechanical pressure but
also extracellular hydrolase.