A spray-induced gene silencing strategy for Spodoptera frugiperda oviposition inhibition using nanomaterial-encapsulated dsEcR

Authors: LI, NINGNING - Huazhong Agricultural University; XU, XIAONA - Huazhong Agricultural University; LI, JIWEN - Huazhong Agricultural University; Hull, Joe; CHEN, LIZHEN - Huazhong Agricultural University; LIANG, GEMEI - Chinese Academy Of Agricultural Sciences

Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2024
Publication Date: 10/19/2024
Citation: Li, N., Xu, X., Li, J., Hull, J.J., Chen, L., Liang, G. 2024. A spray-induced gene silencing strategy for Spodoptera frugiperda oviposition inhibition using nanomaterial-encapsulated dsEcR. International Journal of Biological Macromolecules. 281. Article 36503. https://doi.org/10.1016/j.ijbiomac.2024.136503.
DOI: https://doi.org/10.1016/j.ijbiomac.2024.136503

Interpretive Summary: Targeted disruption of the molecular mechanisms underlying insect reproduction has enormous potential for pest management. For most insects, reproduction is tightly regulated by juvenile hormone (JH) and 20-hydroxyecdysone (20E). The actions of both are mediated by dimeric nuclear receptors, JH with a dimeric pair composed of methoprene-tolerant (Met) and Taiman, and 20E with the ecdysone receptor (EcR) and ultraspiracle (USP) dimer. The respective nuclear receptor pairs bind to specific DNA sequences to drive expression of reproduction associated genes. To determine how these nuclear receptor genes impact female reproduction in the fall armyworm, the functionality of Met, EcR, and USP was disrupted by RNA interference (RNAi). Reductions in fall armyworm fertility were observed following knockdown of each of the genes with the greatest reductions in egg laying occurring in females treated with double-stranded RNAs targeting EcR. Recently, sprays that incorporate nanoparticles as double-strand RNA carriers/protectants have shown promise as efficient delivery systems for triggering RNAi responses in some insect species. The feasibility of using an RNAi-based nanospray to potentially limit the fertility of fall armyworms in the field by targeting EcR function was examined. The number of eggs deposited by fall armyworms sprayed with nanoparticles that encapsulated double-stranded RNAs for EcR were significantly reduced relative to controls. These findings suggest that targeting EcR may be useful for fall armyworm management and highlight the potential of nanospray delivery systems for field-based pest applications.

Technical Abstract: Although RNAi-based pest management holds great potential as an alternative to traditional chemical control, its efficiency is restricted by dsRNA instability and limited cellular uptake. Using nanomaterials to facilitate dsRNA delivery has shown promise in solving these challenges. In this study, we firstly used RNAi to investigate the role of the juvenile hormone and ecdysteroid signaling pathways genes in reproduction of Spodoptera frugiperda, the fall armyworm. Females in knocked-down treatments of any of the Met, EcR, and USP genes had greatly reduced fertility with the most pronounced inhibitory effects on oviposition observed following EcR knockdown, and thus the dsEcR could be a candidate target for RNAi-based oviposition inhibitory agency. Then a combinatorial spray-induced and nanocarrier-delivered gene silencing (SI-NDGS) approach that targeted EcR was conducted. At 72 h post-spay, the transcript levels of EcR and the oviposition were successfully reduced and inhibited. These findings support the groundwork for further developing novel RNAi-based pest management strategies for S. frugiperda.