Imidazole-modified graphene quantum dots can effectively promote the efficient silencing of the larval cuticle protein gene HaLCP17 in Helicoverpa armigera

Abstract

RNA interference (RNAi) is a pivotal strategy in gene functional analysis and pest management. However, the efficacy of RNAi varies significantly across different insect species, particularly exhibiting limited effectiveness in Lepidopteran insects. Therefore, it is imperative to develop innovative delivery strategies of dsRNA to enhance efficient gene silencing in these insects. In this study, we utilized the globally distributed polyphagous Lepidopteran insect pest Helicoverpa armigera as our research model due to its substantial implications for agriculture and limited success with RNAi-based approaches. Through the utilization of RNAi technique, HaLCP17 was identified as a larval cuticle protein gene with the highest lethality among 61 potential lethal target genes of H. armigera. Additionally, silencing HaLCP17 during the larval stage resulted in a maximum decrease of 2.66-fold in expression, accompanied by a mortality rate of 23.33% after 10 days. The larvae in the treatment group exhibited significant reductions in size and epidermal relaxation, leading to maximum decrease of 28.89% and 53.57% in feeding amount and larval weight respectively. Notably, the introduction of Imidazole-Modified Graphene Quantum Dots (IGQDs), a novel type of quantum dot nanoparticles, into the insect RNAi system demonstrated proficient delivery capability for dsRNA and potentiated gene silencing efficiency. Compared with naked dsRNA treatment, the injection of IGQDs-dsHaLCP17 complex reduced the expression of HaLCP17 by 1.66-fold, on the 10th day after treatment the mortality rate increased by 92.88%, and the eclosion rate decreased by 31.42%. These findings hold great potential for future control and analysis of gene function in Lepidopteran insects.