The Janus kinase/signal
transducers and activators of transcription (JAK/STAT) signaling pathway play a
pivotal role in innate immunity. Among
invertebrates, Domeless receptors serve as the key upstream regulators of this
pathway. In our study on Bactrocera
dorsalis,
we identified three cytokine receptors: BdDomeless1, BdDomeless2, and
BdDomeless3. Each receptor encompasses
five fibronectin-type-III-like (FN III) extracellular domains and a
transmembrane domain. Furthermore, these
receptors exhibit the increased responsiveness to diverse pathogenic
challenges. Notably, only BdDomeless3 is upregulated during symbiont-like viral infections. Moreover, silencing BdDomeless3 enhanced the infectivity of Bactrocera dorsalis cripavirus (BdCV) and B.
dorsalis picorna-like virus (BdPLV), underscoring BdDomeless3’s
crucial role in antiviral defense of B. dorsalis. Following the suppression of Domeless3 expression, six antimicrobial peptide genes displayed decreased expression,
potentially correlating with the rise in viral infectivity. To our knowledge, this is the first study
identifying cytokine receptors associated with the JAK/STAT pathway in
tephritid flies, shedding light on the immune mechanisms of B. dorsalis.