## 1 Introduction  
As the global population and living standards grow, production of abundant, high-quality, safe food is increasingly important. However, pests and pathogens pose serious threats to agriculture and aquaculture. The protection of agricultural products from crop pests, especially pest insects, by chemical pesticides has played a central role in securing food resources. However, various disadvantages of many conventional chemical pesticides have become apparent. For example, because of their broad-spectrum of action, they have a negative impact on beneficial insects such as pollinators and predatory layboetles, and this poses a challenge to biodiversity. In general, synthetic chemical pesticides are slow to decompose in the natural environment, and thus there are concerns about the health of ecosystems because of residual chemical pesticides. The use of extremely large amounts of chemical pesticides over a long time has led to the emergence of pests with acquired resistance to the chemicals. Moreover, synthetic chemical pesticides have been extensively studied and commercialized, hence, the development of innovative synthetic pesticides with novel chemical structures is no longer as easy as it used to be. Furthermore, in aquaculture, especially shrimp farming, concerns have been raised about the ecological impact of the use of large amounts of chemical antibiotics and synthetic antiviral agents that can induce the emergence of drug-resistant pathogens, and thus the development of more natural and environmentally friendly disease-control agents is covered. In the light of this situation, the 2020 report \"Farm to Fork Strategy\" [1] of the European Union (EU), called for halving the overall use and risk of chemical pesticides, and the use of antibiotics in livestock animals and aquaculture by 2030 [2; 3]. One of the most promising alternatives is RNAi-based pesticides and RNAi reagents for viral diseases. The functional ingredient of such RNAi-based products is an RNA molecule with a double-stranded structure (dsRNA). Its action is based on the mechanism of RNA interference (RNAi), which specifically represses the expression of a target gene in a nucleotide sequence-specific manner [4; 5] when the dsRNA is taken up into a cell with RNAi capability (Figure 1). In other words, RNAi-based pesticides function by inhibiting the expression of a gene that is essential for the survival of the target crop pest through the RNAi effect, thereby suppressing vital biology of the pest and even causing death [6; 7]. Thus, such pesticides are also referred to as \"RNA-induced gene silencing pesticides\". RNAi effects by topical dsRNA application have also been studied to control the infection and proliferation of pathogens including fungi, viruses, and viroids in plants [8; 9; 10; 11; 12]. The application of RNAi-based pesticides and antiviral agents can be roughly divided into two categories: the establishment of genetically modified plants expressing dsRNAs that act on target pests, and the exogenous (topical) application of dsRNAs to the plant body (e.g., through foliar spray, irrigation, or trunk injection). The former is a method of pest management using transgenic crops, and the latter is a non-transformative delivery of dsRNA. The focus of this review is on the production of dsRNAs for topical administration, especially for use in foliar spraying of crops. We also discuss the production of dsRNAs in forms that can be applied in feed in shrimp farming [13]. The first advantage of using RNAi-based pesticides as insecticides is that they essentially inhibit the growth of only the target pest(s). As a nucleotide sequence that specifically suppresses the expression of a target gene in the pest to be killed or inhibited is designed,  
Figure 1: RNA interference (RNAi)-based pesticides and antiviral agents: (**a**) RNAi mechanism triggered by double-stranded RNA (dsRNA) and hairpin-type RNA (hpRNA).