Ecdysone Receptor (EcR) and Ultraspiracle Protein (USP) Genes From Conopomorpha sinensis Bradley Eggs: Identification and Expression in Response to Insecticides

Abstract

Conopomorpha sinensis Bradley (Lepidoptera: Gracilariidae) is the dominant insect pest of litchi (chinensis Sonn.) and longan (Euphoria longan Lour.) fruit trees. Management of this pest species is a challenging task due to its cryptic borer behavior. Controlling C. sinensis at the egg stage is the best alternative strategy to chemical control of C. sinensis adults. However, thorough studies regarding the indirect and sublethal effects of chemicals on the different developmental stages of C. sinensis are insufficient. In this study, the effect of some insecticides was evaluated on C. sinensis eggs. The ovicidal activity of chlorbenzuron, abamectin, chlorantraniliprole, and λ-cyhalothrin was confirmed by morphological observation of the defects in C. sinensis eggs. Moreover, we characterized four essential ecdysone receptor proteins in insects [i.e., two isoform ecdysone receptors (EcR: CsEcRA. CsEcRB) and two isoform ultraspiracle proteins (USP: CsUSP1, CsUSP2)] from C. sinensis eggs. The CsEcRA, CsEcRB, CsUSP1, and CsUSP2 genes consisted of 1521-, 1614-, 1410-, and 1236-bp open reading frames which encoded proteins of 506, 527, 469, and 413 amino acid residues, respectively. Furthermore, the embryonic differential responses of CsEcRs, CsUSPs, and vitellogenin receptor (VgR: CsVgR) to insecticides were evaluated by qRT-PCR. Among the five tested genes, CsVgR and CsUSP1 were the most sensitive to all the tested insecticides, with fold change of the expression diminished by 4.27-8.70 times compared with untreated control insects. The data suggests that these insecticidal compounds regulate the expression of these specific proteins, which might eventually lead to reduced viability of C. sinensis eggs. We present here the first data providing molecular elucidation of ecdysone receptor genes and their differential responses to insecticides in C. sinensis eggs. Together with our previous report of insecticide sublethal effects on two reproduction-related genes in C. sinensis adults, CsVgR and CsUSP1

Cyromazine Effects the Reproduction of Drosophila by Decreasing the Number of Germ Cells in the Female Adult Ovary

“…The treatment of insecticides, during different developmental stages of insects, has a significant effect on the mRNA expression level [ 40 ]. A recent study reported that insecticides significantly affected the mRNA expression of EcR and usp [ 41 ], while in Drosophila larvae the treatment of cyromazine reduced ecdysone signaling [ 10 ]. However, the response of ecdysone signaling to insecticides is poorly understood.…”

Recent development in ecdysone receptor of crustaceans: current knowledge and future applications in crustacean aquaculture

“…The active form of ecdysone, that is 20E, is activated after binding with EcR, a member of the nuclear receptor (NR) superfamily. EcR may form heterodimer complex with other nuclear receptors, that is retinoid X receptor (RXR) in crustaceans (Dai et al 2016; Gong et al 2016) or ultraspiracle (USP) in insects (Iwema et al 2009; Yao et al 2020). There was a growing interest in the study of EcR in crustaceans compared to insects since 1992 (Fig.…”

“…The activation of EcR would then bring about a cascade of downstream events, that is the upregulation of myriad of genes regulating various moult‐related processes, such as cuticle release, osmotic flux, and chitin biosynthesis and degradation (Song et al 2017). Among arthropods, EcR in insects has been more extensively studied compared to their crustacean counterparts, as EcR is the primary target for the production of transgenic pest resistance crops (Zhu et al 2012; Yu et al 2014) or endocrine‐disrupting chemicals such as insecticides (Uchibori‐Asano et al 2019; Yao et al 2020) for pest control purposes.…”

Hormonal regulations in insect metamorphosis: A review

“…The receptors specifically binding 20-hydroxyecdysone are called the ecdysone receptors (EcR) [36] . An EcR protein pair with an Ultraspiracle (Usp) protein to form an active molecule [37] . The structure of EcR mediate DNA binding, spliced to make two major isoforms, EcR-A and EcR-B.…”