Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) are two globally concerning quarantine pests within the genus Bactrocera (Tephritidae). Both species inflict severe damage on the agricultural industry and international export trade. Their distribution range has expanded due to global warming, posing an increasing threat to fruit production. Heat shock proteins (HSPs), functioning as molecular chaperones, are known to contribute to temperature adaptation in insects. However, the cold adaptation regulatory mechanisms in these two Bactrocera species remain unclear. In this study, eIF4EBP3-/- mutations were established by the CRISPR-Cas9 system in both species. The survival rate of the mutations was significantly reduced with cold treatments, and qRT-PCR analysis indicated that eIF4EBP3 regulates the expression of several downstream heat shock proteins, suggesting that it may be involved in rapid cold hardening (RCH) adaptability in both fruit fly species. In addition, this work represents the first application of the CRISPR-Cas9 system in B. correcta, which provides methods to further studies on this species. Our results provide insights into the molecular mechanisms underlying rapid cold hardening adaptation in B. dorsalis and B. correcta and a potential molecular marker for monitoring cold tolerance in field populations which could guide the development of novel control strategies that target the RCH adaptation pathways.
