Transcription and functional analysis of phosphine fumigation regulating heat responses in Bactrocera dorsalis

The oriental fruit fly, Bactrocera dorsalis, is a highly destructive pest in fruits, vegetables and flowers with heat treatment being common for its control in internationally traded produce. However, heat treatment can adversely affect quality, which limits its application. This study aimed to develop a novel control strategy combining phosphine fumigation with heat treatment (P + H), demonstrating a significant synergistic effect in controlling B. dorsalis. We conducted transcriptomic analysis and qRT-PCR validation to explore this synergistic effect. P + H significantly increased the expression of heat shock proteins (HSP), but their levels were lower than those induced by heat treatment alone. RNAi-based experiments confirmed the association between HSP gene expression and insect mortality, further supporting the important role of HSP genes in response to heat treatment. Functional enrichment analysis indicated that the MAPK/ERK signaling pathway and HSF-1 dephosphorylation dynamically regulate HSP genes expression under P + H treatment. Additionally, energy allocation toward cellular repair may further limit HSP gene synthesis, affecting insect tolerance to heat response. These findings provide insights into the molecular bases for the synergism of P + H treatment, highlighting that HSP gene regulation plays as critical role in insect stress resistance and offering a novel approach to pest control.