Many plants possess defensive traits that enable them to naturally tolerate and/or deter insect herbivory (host plant resistance; HPR), and selecting for HPR traits in crop cultivars can significantly enhance productivity while providing effective and sustainable insect pest management. However, expression of HPR traits is highly context dependent, and many factors can alter the level of HPR expression, including abiotic stressors associated with global climate change. In the short-term, these factors may reduce HPR efficacy and increase plant susceptibility to herbivory. However, the longer-term consequences of these interactions remain unclear, particularly the extent to which these changes also select for or favor insect adaptions to overcome HPR (e.g. virulence). To better understand these evolutionary interactions, we tested how one abiotic stressor, flooding, impacts the invasive, pestiferous soybean aphid, Aphis glycines. We quantified transcriptomic responses in both virulent and avirulent aphids on different soybean cultivars (e.g. HPR or aphid-susceptible) and under different flood stress treatments. Aphid fitness was also directly measurement through mesocosm studies. Correlating these molecular changes in aphids with phenotypic data will increase our knowledge of the mechanisms that underly virulence and the population-level factors that influence its spread.