Peptidoglycan recognition proteins (PGRPs) are important components of insect immune systems, in which they play key roles. We cloned and sequenced two full-length PGRP, named OfPGRP-A and OfPGRP-B, from the Asian corn borer, Ostrinia furnacalis. These two genes comprise open reading frames of 658 and 759 bp, encoding proteins of 192 and 218 amino acids, respectively. qPCR showed that OfPGRP-A and OfPGRP-B are prominently expressed in the midgut of O. furnacalis fourth instar larvae. After inoculation with Staphylococcus aureus and Bacillus thuringiensis, the expression of OfPGRP-A was significantly upregulated, whereas the expression of OfPGRP-B was enhanced after inoculation with Escherichia coli. This suggests that OfPGRP-A mainly recognizes Gram-positive bacteria and may participate in the Toll signaling pathways, while OfPGRP-B identifies Gram-negative bacteria and may participate in Imd signaling pathways. Our results provide insights into the roles of PGRPs in O. furnacalis immune function and a foundation for using pathogens for the biological control of O. furnacalis.

Spodoptera frugiperda is a globally significant migratory agricultural pest that requires proactive monitoring. Understanding the molecular mechanisms underlying the interactions between pathogenic microorganisms and S. frugiperda is crucial for enhancing the effectiveness of microbial control agents against this pest. This study used transcriptome sequencing and molecular biology techniques on S. frugiperda larvae infected by bacteria and fungi to investigate the composition and molecular regulatory mechanisms of its immune system. A total of 598 immune-related genes were identified. Upon microbial infection, most immune-related genes showed an upregulated expression trend. Phylogenetic analysis revealed that the immune gene repertoire of S. frugiperda is relatively conserved. The expression of the genes of peptidoglycan recognition proteins in different tissues of S. frugiperda induced by microorganisms at different times was verified using qPCR, and the results confirmed that these genes were significantly upregulated under specific pathogenic infections. This study elucidates the immune transcriptome of S. frugiperda in response to various pathogenic microorganisms, providing valuable insights for improving the effectiveness of existing microbial agents and developing new, highly efficient, and specific biopesticides.

This study explores the molecular mechanisms underlying diapause in the parasitoid wasp Telenomus remus (Nixon) (Hymenoptera: Platygastridae), a critical egg parasitoid for the biological control of the invasive pest Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). While effective in pest management, T. remus faces limitations in large-scale applications due to its short lifespan and low viability under storage conditions. Diapause, a state of developmental arrest, was successfully induced in T. remus using photoperiod manipulation (0L:24D), allowing for extended survival and improved storage potential. Transcriptome sequencing identified 2642 differentially expressed genes, with 617 involved in 284 enriched pathways, including calcium signaling and phototransduction. The study found that the expression levels of CBP1 and CBP2, genes encoding calcium-binding proteins, were significantly downregulated during diapause. As key regulators in calcium ion-mediated signal transduction pathways, the downregulation of CBP1 and CBP2 may lead to the suppression of intracellular calcium signaling, thereby affecting light signal transduction and energy metabolism regulation. This suggests that during diapause, insects may reduce calcium signaling activity to suppress physiological functions, maintain a low metabolic state, and decrease sensitivity to environmental stimuli. Additionally, ARR genes still exhibited differential expression, further supporting their potential role in phototransduction and diapause regulation.

Spodoptera frugiperda is a globally significant migratory agricultural pest that requires proactive monitoring. Understanding the molecular mechanisms underlying the interactions between pathogenic microorganisms and S. frugiperda is crucial for enhancing the effectiveness of microbial control agents against this pest. This study used transcriptome sequencing and molecular biology techniques on S. frugiperda larvae infected by bacteria and fungi to investigate the composition and molecular regulatory mechanisms of its immune system. A total of 655 immune-related genes were identified, including pattern recognition receptors, signal transduction factors, immune effectors, and immune regulators. Following microbial infection, most immune-related genes showed an upregulated expression trend. Phylogenetic analysis revealed that the immune gene repertoire of S. frugiperda is relatively conserved. The expression changes of immune recognition receptors PGRP and βGRP were validated using qPCR, confirming that these genes were significantly upregulated under specific pathogenic infections. This study elucidates the immune transcriptome of S. frugiperda in response to various pathogenic microorganisms, providing valuable insights for improving the effectiveness of existing microbial agents and developing new highly efficient and specific biopesticides.

To elucidate the role of the peptidoglycan recognition protein OfPGRP-B in the innate immunity of Ostrinia furnacalis, a recombinant expression system was established using a prokaryotic expression strategy. The recombinant plasmid encoding OfPGRP-B was constructed and expressed in Escherichia coli, and the target protein was successfully obtained after induction. Purification and Western blot analysis confirmed that the molecular weight of the recombinant protein was consistent with the predicted value. The immune functions of OfPGRP-B were further investigated through antibacterial activity assays, bacterial agglutination tests, amidase activity assays, phenoloxidase (PO) cascade activation, and in vivo melanization assays. The results showed that OfPGRP-B alone exhibited weak direct antibacterial activity against the tested bacteria but significantly promoted bacterial agglutination and was capable of degrading peptidoglycan derived from E. coli and Staphylococcus aureus. In the presence of bacterial peptidoglycan, OfPGRP-B enhanced the activation of the PO cascade, but had no significant effect on in vivo melanization. These findings suggest that OfPGRP-B may function as an immunomodulatory factor involved in the humoral immune response of O. furnacalis, providing a theoretical basis for the development of biological control strategies based on host immune mechanisms.

Ostrinia furnacalis Guen?e is an important pest of maize. The current use of microbial agents to control O. furnacalis have been relatively successful. However, upon infestation with microorganisms, O. furnacalis initiates an innate immune response to defend itself against foreign invaders. Therefore, understanding the immune mechanisms in O. furnacalis is important to ensure a more efficient use of microbial agents for the control of this pest. In the present study, a gram-positive bacterium, Staphylococcus aureus, and a gram-negative bacterium, Escherichia coli, were used to induce an immune response in O. furnacalis. Transcriptomic sequencing was then used to screen for genes that were significantly differentially expressed after microbial induction and sequence comparison and phylogenetic analysis to identify immune-related genes the expression of which was significantly induced. The results show a large number of genes were differentially expressed in O. furnacalis after microbial induction, the majority of which were immune-related genes. The expression of some immune-related genes such as those encoding antimicrobial peptides, peptidoglycan recognition proteins and serine protease inhibitors were strongly induced. Overall, our study increases the understanding of the mechanism of the innate immune response in O. furnacalis and provides a theoretical basis for better biological control using microbial agents.