Molecular Characterization of Vitellogenin and Its Receptor in Spodoptera frugiperda (J. E. Smith, 1797), and Their Function in Reproduction of Female

Abstract

The fall armyworm Spodoptera frugiperda is a highly polyphagous invasive pest. The strong reproductive capacity is an important factor in the rapid colonization and expansion of S. frugiperda. Vitellogenin (Vg) and vitellogenin receptor (VgR) play important roles in insect reproduction. As the precursor of vitellin (Vn), Vg provides essential nutrition for embryonic development, and VgR mediates the uptake of Vg by oocytes. In this context, we cloned and characterized these two genes of S. frugiperda (SfVg and SfVgR) and evaluated their expression profiles in different developmental stages and tissues. The RNA interference experiment was used to investigate their function in vitellogenesis. The ORF values of SfVg and SfVgR were 5250 and 5445 bp, encoding 1749 and 1815 amino acid residues, respectively. The qRT-PCR results revealed that both SfVg and SfVgR were highly expressed in female adults; SfVg was specifically expressed in the fat body, whereas SfVgR was highly expressed in the ovary. In addition, the depletion of either SfVg or SfVgR hindered oocyte maturation and ovarian development, leading to a significant decrease in fecundity. The present study reveals the importance of SfVg and SfVgR in the vitellogenesis of S. frugiperda, laying a theoretical foundation for the development of pollution-free pest control strategies with SfVg and SfVgR as new targets.

Insights from different reproductive gene knockdowns via RNA interference in the lady beetle Eriopis connexa: Establishing a new model for molecular studies on natural enemies

“…Interestingly, silencing of Vg genes appears to interfere with EcVgR expression. This feedback loop has also been reported in S. frugiperda (Han, Wang, et al, 2022), although it is not common across insects (Hu et al, 2019; Lu et al, 2015). Finally, treatment with ds VgR silenced EcVgR but did not interfere with EcVg1 or EcVg2 expression after 48 h. The feedback loop here is not evident but cannot be excluded since, when VgR was knocked down in S. frugiperda , the expression of Vg decreased compared to that in the control after 72 h (Han, Wang, et al, 2022).…”

“…Moreover, given that the pattern of gene expression can be associated with physiological functions (Han, Wang, et al, 2022), we examined the expression levels of EcVg1 , EcVg2, and EcVgR in females of different ages. In E. connexa , female sexual maturity typically occurs approximately 5–6 days after emergence (DAE) (Silva et al, 2021).…”

“…These results are similar to those obtained for A. grandis grandis (Coelho et al, 2016), suggesting that the knockdown of Vg or VgR did not influence egg production over the 15‐day period in these two coleopterans. However, in other insects, such as H. axyridis , S. frugiperda , and Triatoma infestans (Klug) (Hemiptera: Reduviidae), when Vg or VgR was silenced, fewer eggs were laid, or oviposition stopped (Blariza et al, 2017; Han, Han, et al, 2022; Han, Wang, et al 2022). Interestingly, this difference does not appear to be dose dependent since, when comparing E. connexa and H. axyridis , the two species are similar in size, and the dsRNA doses applied for VgR were similar—500 ng for the first and 600 ng for the last (Han, Han, et al, 2022).…”

“…For example, in Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), silencing Vg and VgR resulted in reduced ovary size, decreased egg production, a shortened oviposition period, and an extended preoviposition period in females (Han, Wang, et al, 2022). In Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), silencing RfVg extended the preoviposition period, reduced egg quantity, significantly lowered egg viability, and induced alterations in egg and ovary phenotypes (Rasool et al, 2021).…”

Effect of Three Novel Thiazolidiones on the Development, Reproduction, and Trehalase Activity of Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…This may have been because of the differences in the physiological functions and morphological structures between larvae and pupae in Lepidoptera insects, resulting in different affinities of the three compounds for trehalase in the larvae and pupae. Multiple studies have demonstrated that vitellogenesis can directly affect insect reproduction and is essential when studying reproductive regulation [52][53][54]. The expression of SfVg and SfVgR in the female adults of the treatment group in our study exhibited significant upregulation and downregulation, respectively, on the fourth day of eclosion.…”