Background: Solenopsis invicta, commonly known as the red imported fire ant (RIFA), is an important global invasive pest, and its management is challenging because of insecticide resistance and environmental problems. Methods: In this research, we applied transcriptomics to analyze the molecular responses of S. invicta worker ants exposed to different types of pesticides, beta-cypermethrin (BC) and the entomopathogenic fungus Cordyceps cicadae (CC), as well as to different concentrations of these pesticides. Results: A total of 2727 differentially expressed genes (DEGs) were identified across all samples. The number of DEGs in the BC treatment group was significantly higher than that in the CC treatment group (2520 vs. 433), and higher concentrations resulted in more DEGs (an increase of 47 in the BC group and 229 in the CC group). KEGG pathway analysis revealed that the DEGs were significantly enriched in lipid metabolism, carbohydrate metabolism, amino acid metabolism, signal transduction, and membrane transport. Immune-related gene analysis showed more general down-regulation (average FPKM value in BC 741.37 to 756.06 vs. CK 1914.42) of pathogen recognition genes (PGRP-SC2) under BC stress conditions, while CC treatment resulted in increases in expression of important immune effectors such as various serine proteases. Conclusions: Overall, this study provides useful insights into the molecular basis of responses to different pesticides in S. invicta and offers a basis to develop new approaches to control this pest.
Cai et al. (2026) studied this question.