Chitosan double-stranded RNA nanocomplexes for Piezodorus guildinii control

Piezodorus guildinii (Westwood, Hemiptera: Pentatomidae) causes economic losses in soybean crops by diminishing productivity, impacting grain size, oil content, and germination power. RNA interference (RNAi), a conserved gene regulation process initiated by double-stranded RNA (dsRNA), may be used as a safe technique in integrated pest management strategies. Conjugating dsRNA with cationic polymers, which protect dsRNA from degradation has shown to enhance this response. This study aims to assess the impact of dsRNA administration on the viability of P. guildinii and evaluate dsRNA-chitosan nanocomplexes as a pest control strategy.

Ten target genes were selected, dsRNAs were designed and synthesized. In injection assays, significant mortality exceeding 76% was observed, while mortality from ingestion also showed significant differences, reaching 49%. The dsRNA targeting Srp54k gene was selected and a chitosan-dsRNA nanocomplex was synthesized. These nanocomplexes demonstrated enhanced stability under RNase treatment in vitro, and, in in vivo assays, a cumulative corrected mortality rate of 66% was reported. Consistent with these findings, RT-qPCR analysis revealed that gene expression levels in treated insects were significantly reduced compared to control at 24, 48, and 72 h post treatment for targeted genes.

In this work, we evaluated the effect of dsRNA administration by injection and ingestion on the viability of P. guildinii and determined its molecular silencing effects. Additionally, we synthesized and characterized chitosan-dsRNA nanoparticles, which demonstrated improved efficacy in terms of stability. These findings are promising for the development of new integrated management strategies for stink bugs control. © 2025 Society of Chemical Industry.