BACKGROUND: Temperature and humidity are critical environmental factors that shape insect growth, development and survival. The larval stage is particularly vulnerable, making the ability to detect and respond to adverse environmental conditions vital for avoiding harm. The oriental fruit fly, Bactrocera dorsalis, is a major global pest inflicting damage on >
150 fruit crops. However, the behavioral responses of nonmodel insect larvae to temperature and humidity remain poorly characterized. RESULTS: We found that temperature and humidity significantly influence key larval behaviors. To uncover the molecular mechanisms driving these behaviors, we identified B. dorsalis painless (Bdorpainless) homologs and confirmed their expression during larval behavioral stages. Genetic disruption of Bdorpainless notably impaired the larvae's temperature-escape response. Although humidity sensing remained unaffected in Bdorpainless-mutant larvae, their pupation rate was significantly reduced. CONCLUSIONS: Our findings provide new insights into the role of environmental factors in B. dorsalis behavior and highlight Bdorpainless as a potential molecular target for pest control. For example, RNA-based biopesticides targeting Bdorpainless could impair larvae's environmental adaptability, offering a novel pest management approach. © 2025 Society of Chemical Industry.