## 1 Introduction  
In insects, including oviparous species, successful reproduction is fundamental in maintaining their population, which relies on two key indispensable steps: vitellogenin (Vg) biosynthesis and deposition. After being synthesized in the fat body and released into the hemolymph, Vg is taken up into the developing ovaries via endocytosis by its receptor, vitellogenin receptor (VgR), which is located on the surface of the oocytes within clathrin-coated pits [1]. Then, this lipoprotein is transported to its target recipient cell by VgR, providing multiple nutritional elements to support the developments of oocytes [2].  
It is documented that only a single VgR gene exists in most insect species, which could generate a long transcript, about 7.5 kb, and encode an ovary-specific polypeptide with a molecular weight of 180-214 kDa, approximately twice the VgR in vertebrates [1]. _In silico_ analysis further suggests that insect VgR is a member of the low density lipoprotein receptor (LDLR) superfamily, which is characterized by five highly conserved, but functionally different, amino acids domains: the ligand-binding domain (LBD) containing several Class A cysteine-rich repeats (LDLRa), the epidermal growth factor (EGF)-precursor domain comprising Class B cysteine-rich (LDLRb, EGF-like repeats) and YWXD repeats, the O-linked sugar domain, the transmembrane domain, and the cytoplasmic tail domain with internalization signals [3].  
The molecular characteristics of VgRs are not only identified in invertebrates, like insects [3], mites [4], ticks [5; 6; 7], shrimps [8; 9; 10], crabs [11], and nematodes [12], but also in vertebrates, such as fish [13; 14; 15; 16], frogs [17] and chickens [18]. However, only five VgRs have been identified in Dipteran insects, including _Aedes aegypti_[19], _Anopheles gambiae_[20], _Ceratitis capitata_ (genomic sequence), _Drosophila melanogaster_[21] and _Musca domestica_ (genomic sequence). Therefore, there is not enough available information to get the full understanding of the reproductive mechanism of this order, considering its economic importance.  
The oriental fruit fly, _Bactrocera dorsalis_ (Hendel), is one of the most devastating pests of fruits and vegetables throughout some areas of Asia and the Pacific, causing grave economic losses [22]. Unfortunately, there is still lack of effective strategies to manage this pest, owing to its unique biological properties, such as the rapidly increased insecticide resistance, high fecundity and oviposition traits [22; 23; 24]. Although, the yolk protein genes of this species, _Bdyp1_ and _Bdyp2_, have been well investigated in previous study [25], the information on their receptor is still lack. Thus, illustrating the function of VgR in \(B\). _dorsalis_ will help obtain a more comprehensive understanding of the process of reproduction, and eventually develop new strategies to control this pest.  
In this research, we identified the full-length of VgR from \(B\). _dorsalis_ (\(Bd\)VgR), analyzed and compared the basic molecular and structural characteristics with those from other insects. In addition, we reported the spatial- and temporal-expression pattern of \(Bd\)VgR by semi-quantitative PCR and quantitative PCR (\(q\)PCR), along with the expression profiles of its ligands (_Bdyp1_ and _Bdyp2_) and -ovarian development in time course. Finally, we further verified the function of _Bd_VgR by silencing its expression by RNA interference (RNAi).