Technological breakthroughs

In the context of sustainable agricultural development, reduced reliance on synthetic chemicals, and growing concerns over environmental impacts, a range of biopesticide technologies are being actively researched and developed. Among these, RNA interference (RNAi)–based biopesticides are emerging as a novel approach that exploits natural gene-regulation mechanisms to control agricultural pests.

RNA Interference (RNAi) Mechanism

RNA is a biological molecule naturally present in all living organisms. RNA interference (RNAi) is a conserved biological mechanism in which specific RNA molecules suppress gene expression at the post-transcriptional level.

In RNAi-based biopesticides, double-stranded RNA (dsRNA) molecules are designed to target essential genes in specific pest species. Once dsRNA enters insect cells, it is processed by Dicer enzymes into small interfering RNAs (siRNAs), which are incorporated into the RNA-induced silencing complex (RISC). This complex then degrades the corresponding messenger RNA (mRNA), effectively “silencing” the target gene and impairing the pest’s survival or development.

Use of Yeast as an RNAi Delivery System

One of the major challenges of RNAi technology is the limited stability of dsRNA in field conditions and the difficulty of producing RNAi agents at industrial scale. Recent studies indicate that yeast-based delivery systems offer a potential solution.

In this approach, yeast cells are engineered to produce and encapsulate dsRNA within their cellular structure. Prior to application, the yeast is inactivated and formulated into a sprayable solution that can be applied to crops in a manner similar to conventional plant protection products. The yeast matrix helps protect dsRNA from environmental degradation caused by sunlight, temperature, and moisture.

When insect pests consume treated plant material, dsRNA is released in the digestive tract and can initiate RNAi-mediated gene silencing.

Biological Factors Affecting RNAi Effectiveness

According to scientific reviews published in Frontiers in Physiology, the effectiveness of RNAi in pest control varies considerably among insect species and depends on multiple biological factors:

• Species-specific RNAi sensitivity: Some insect species exhibit strong and persistent RNAi responses, while others show weak or inconsistent gene silencing.
• Systemic versus non-systemic RNAi: Many insects lack systemic RNAi mechanisms, meaning the silencing effect may be limited to tissues directly exposed to dsRNA, often the gut.
• Presence of dsRNA-degrading enzymes: Digestive enzymes (dsRNases) in some insects can rapidly degrade dsRNA before cellular uptake, reducing RNAi efficiency.
• Cellular uptake mechanisms: dsRNA entry into insect cells depends on transport proteins or endocytosis pathways, which differ across insect taxa.

These factors indicate that the development of RNAi-based biopesticides requires species-specific design strategies, along with delivery technologies that protect dsRNA and enhance cellular uptake.

Key Characteristics of RNAi-Based Biopesticides

Compared with conventional chemical pesticides, RNAi-based biopesticides exhibit several notable characteristics:

• High specificity, as dsRNA sequences are designed for individual pest species.
• Biodegradability, with limited long-term environmental persistence.
• Potential role in resistance management, due to a mode of action distinct from traditional chemical active ingredients.

Application Prospects

At present, RNAi-based biopesticides remain in stages of research, field testing, and regulatory evaluation in many countries. Beyond crop protection, yeast-based RNAi platforms are also being explored for other agricultural applications, including disease prevention in livestock via feed-based delivery systems.

In the long term, RNAi technology is considered a complementary innovation that may diversify pest management tools and contribute to safer, more efficient, and more sustainable agricultural production systems.

Topical application of BioClay allows for extended RNAi-mediated protection from plant viruses. BioClay is a complex of double-stranded RNA (dsRNA) and layered double hydroxide (LDH). BioClay is prepared by mixing dsRNA and LDH in solution and is applied as a foliar spray. Moisture and carbon dioxide combine to allow acid release of the dsRNA, with LDH degrading to its constituents. The dsRNA can subsequently be taken up by the plant and prime its RNA machinery to degrade homologous viral RNAs. Due to the stabilization and slow release of dsRNA, resistance to the target virus relative to naked dsRNA can be extended from days to weeks.