Sex-Specific Thermal Adaptation in Riptortus pedestris: Integrating Logistic Thresholds and Transcriptomic Responses

The bean bug Riptortus pedestris (Hemiptera: Alydidae) is a major soybean pest in Asia, increasingly threatened by rising temperatures. It is crucial to clarify the high-temperature lethal thresholds of R. pedestris for predicting population dynamics under climate warming. Previous physiological data showed that female adults have significantly higher heat tolerance than males, with HLT50 values of 39.76 °C versus 38.45 °C and HLT90 values of 42.99 °C versus 42.44 °C. This sex-specific difference suggests distinct molecular responses to thermal stress. To test this hypothesis, we performed transcriptome sequencing of adults exposed to 24 °C (control), 40 °C (sublethal), and 44 °C (lethal), with males and females treated separately. A high-quality assembly yielded 270,199 unigenes, with 71 heat shock protein (HSP) genes identified across six subfamilies (sHSP, HSP40, HSP60, HSP70, HSP90, HSFs). HSPs exhibited a dual strategy: constitutive expression for basal proteostasis and strong induction—especially at 44 °C—for stress defense. Notably, responses were sexually dimorphic: females upregulated multiple stress-responsive HSPs (e.g., RpedHsp15.5-3, RpedHsp30.8) to protect reproduction, while males specifically induced RpedHsp83.6, possibly for signaling regulation. Phylogenetic analysis confirmed conservation within Hemiptera. These findings reveal the molecular basis of thermal adaptation in R. pedestris and identify key HSPs as potential targets for RNAi, HSP inhibitors, or precision thermal control.