An Integrative Analysis of Transcriptomics and Proteomics Reveals Novel Insights into the Response in the Midgut of Spodoptera frugiperda Larvae to Vip3Aa

The insecticidal Vip3 proteins, secreted by Bacillus thuringiensis (Bt) during its vegetative growth phase, are currently used in Bt crops to control insect pests, and are genetically distinct from known insecticidal Cry proteins. Compared with Cry toxins, the mechanisms of Vip3 toxins are still poorly understood. Here, the responses of Spodoptera frugiperda larvae after Vip3Aa challenge are characterized. Using an integrative analysis of transcriptomics and proteomics, we found that Vip3Aa has enormous implications for various pathways. The downregulated genes and proteins were mainly enriched in metabolic pathways, including the insect hormone synthesis pathway, whereas the upregulated genes and proteins were mainly involved in the caspase-mediated apoptosis pathway, along with the MAPK signaling and endocytosis pathways. Moreover, we also identified some important candidate genes involved in apoptosis and MAPKs. The present study shows that exposure of S. frugiperda larvae to Vip3Aa activates apoptosis pathways, leading to cell death. The results will promote our understanding of the host response process to the Vip3Aa, and help us to better understand the mode of action of Vip3A toxins.