Cytochrome P450 Genes Mediate High-Temperature Adaptation Under Diverging Humidity Conditions in Tuta absoluta

Temperature and humidity are critical abiotic factors shaping the survival and adaptation of insect pests. However, the molecular mechanisms underlying high-temperature tolerance under contrasting humidity conditions remain poorly understood, particularly in globally invasive species such as the tomato pinworm, Tuta absoluta. Previous studies have examined individual stressors, leaving interactive thermo-hygrometric effects on gene expression and survival insufficiently resolved. Here, we assessed the contribution of cytochrome P450 genes to thermal adaptation under low- and high-humidity conditions using transcriptome profiling combined with nanocarrier-mediated RNA interference (RNAi). Third-instar larvae were exposed to high temperature under low humidity (HT-LH: 40 °C, 50% RH) or high humidity (HT-HH: 40 °C, 75% RH) for eight hours. Survival declined from 97.5% in the control to 74.16% under HT-LH and 68.33% under HT-HH conditions. Transcriptome analysis revealed extensive differential gene expression, with 464 genes upregulated and 565 downregulated in HT-LH, and 1145 upregulated and 1166 downregulated in HT-HH. Functional annotation highlighted pathways linked to metabolic regulation, proteostasis, and detoxification, including multiple cytochrome P450-associated processes. RT-qPCR confirmed the upregulation (3–5 fold) of four P450 genes (CYP6AB327, CYP6ABF1b, CYP6AE214, and CYP9A306c) under high temperature across both humidity regimes. RNAi-mediated silencing of these genes significantly reduced larval survival, demonstrating their functional role in thermal-hygrometric stress tolerance across. Cytochrome P450 genes underpin the adaptive capacity of the tomato pinworm to high-temperature stress across contrasting humidity conditions, highlighting RNAi-based disruption of P450 function as a promising avenue for sustainable pest management under climate change scenarios.