Increased Phenoloxidase Activity Constitutes the Main Defense Strategy of Trichoplusia ni Larvae against Fungal Entomopathogenic Infections

The cabbage looper Trichoplusia ni is an important agricultural pest worldwide and frequently used as a model organism for assessing entomopathogenic fungi virulence, though few studies have measured the host response repertoire to fungal biocontrol agents. Here, we quantified immune of T. larvae following exposure two species: Beauveria bassiana Cordyceps javanica. Results from our study demonstrate that exposed entomopathogens had higher total phenoloxidase activity compared controls, indicating melanization cascade one main components driving defense against infection contrasting observations other insect–fungi interaction studies. We also observed differences in depending on species fungi, with significantly induction during infections B. than C. Larvae increased expression genes involved prophenoloxidase Imd, JNK, Jak/STAT signaling pathways. Our results indicate notable absence Toll pathway-related responses, further pathosystems. Important were antimicrobial effectors, eliciting three effectors (lysozyme, gloverin, cecropin), while javanica only induced cecropin expression. These provide insight into strategies employed by protection increase understanding insect–fungal entomopathogen interactions, aiding design more effective microbial control this pest.