Characterization of two Bursicon genes and their association with wing development in the brown citrus aphid, Aphis citricidus

Abstract

The tanning hormone, Bursicon, is a neuropeptide secreted by the insect nervous system that functions as a heterodimer composed of Burs‐α and Burs‐β subunits. It plays a critical role in the processes of cuticle tanning and wing expansion in insects. In this study, we successfully identified the AcBurs‐α and AcBurs‐β genes in Aphis citricidus. The open reading frames of AcBurs‐α and AcBurs‐β were 480 and 417 bp in length, respectively. Both AcBurs‐α and AcBurs‐β exhibited 11 conserved cysteine residues. AcBurs‐α and AcBurs‐β were expressed during all developmental stages of A. citricidus and showed high expression levels in the winged aphids. To investigate the potential role of AcBurs‐α and AcBurs‐β in wing development, we employed RNA interference (RNAi) techniques. With the efficient silencing of AcBurs‐α (44.90%) and AcBurs‐β (52.31%), malformed wings were induced in aphids. The proportions of malformed wings were 22.50%, 25.84%, and 38.34% in dsAcBurs‐α‐, dsAcBur‐β‐, and dsAcBurs‐α + dsAcBur‐β‐treated groups, respectively. Moreover, feeding protein kinase A inhibitors (H‐89) also increased the proportion of malformed wings to 30.00%. Feeding both double‐stranded RNA and inhibitors (H‐89) significantly downregulated the wing development‐related genes nubbin, vestigial, notch and spalt major. Silence of vestigial through RNAi also led to malformed wings. Meanwhile, the exogenous application of 3 hormones that influence wing development did not affect the expression level of AcBursicon genes. These findings indicate that AcBursicon genes plays a crucial role in wing development in A. citricidus; therefore, it represents a potential molecular target for the control of this pest through RNAi‐based approaches.