Laboratory Testing of RNA Interference (RNAi) Technology for Pest Control

Insect pests cause crop yield losses and spread plant viruses. Modern agriculture therefore faces major challenges in controlling pests in an environmentally friendly way. 

Chemical pesticides are indeed effective, but they cause environmental pollution, promote pest resistance, and kill non-target insects that serve as natural enemies of pests. With advances in technology, a new promising method has emerged for controlling insect pests: RNA interference (RNAi), a technique that is highly specific to certain species, low-risk, effective, and environmentally friendly.

RNAi is a natural mechanism used to regulate specific genes in most eukaryotic organisms. This mechanism works when double-stranded RNA (dsRNA) enters the cell. The dsRNA is processed by an enzyme called Dicer into small fragments known as small interfering RNA (siRNA). 

The siRNA then associates with proteins to form an RNA-silencing complex called the RNA-induced silencing complex (RISC). RISC is guided to bind target mRNA, leading to the degradation of the mRNA and the suppression of gene expression.

RNAi can be engineered to silence essential genes in pests, causing them to lose the ability to survive, reproduce, or feed on plants.

• How Is RNAi Used for Pest Control?
• How Do Insects Respond to RNAi-Based Pesticides?
• Advantages and Challenges of RNAi as a Pesticide
• Challenges in RNAi Application

How Is RNAi Used for Pest Control?

The application of RNAi technology in insects can be carried out through microinjection, feeding, and soaking methods.

1. Microinjection

Microinjection involves injecting dsRNA directly into the insect’s body or embryo. This method has been successful in Drosophila melanogaster, where it was used to silence the frizzled gene. However, microinjection is not suitable for field pest control because it requires high technical skill and is only practical for small insects.

2. The Oral

The oral method involves adding synthetic dsRNA or microbe-produced dsRNA to the insect diet. This method is more practical because it requires less labor and is suitable for field applications, especially for insects like beetles (Coleoptera).

However, RNAi via oral delivery is less effective in many insect species. For example, Locusta migratoria shows very low RNAi effectiveness when dsRNA is provided through feeding.

The main reason for this reduced effectiveness is the presence of dsRNase enzymes in the insect gut that degrade dsRNA.

C. Soaking

Another method is soaking, commonly used in insect cell culture, where dsRNA is added to the culture medium. There is also a topical method, where dsRNA or siRNA formulations are applied to the insect’s body surface.

These molecules can penetrate the insect cuticle and cause mortality.

How Do Insects Respond to RNAi-Based Pesticides?

(source: Freepik.com)

Not all insect species respond equally to dsRNA or RNAi. Among various insect groups, beetles (Coleoptera) are generally highly responsive to RNAi.

A dsRNA-binding protein called Staufen C plays a key role in successful RNAi in beetles. This gene is found only in Coleoptera and is essential for processing dsRNA into siRNA.

RNAi responsiveness depends on several factors:

• the type of tissue that absorbs the dsRNA
• gut environment (especially for oral delivery)
• degradation of dsRNA by nucleases
• dsRNA becoming trapped inside cells and unable to be processed into siRNA

Overall, RNAi works by inhibiting essential genes in insect pests using dsRNA, leading to reduced physiological function, developmental disruption, or death.

This application has strong potential as an alternative to chemical insecticides. RNAi can be directed at specific genes that are crucial for insect survival.

Advantages and Challenges of RNAi as a Pesticide

Main advantages of RNAi-based pest control:

• Highly specific:RNAi affects only the target pest because the gene sequence must match the dsRNA, making it safe for non-target organisms.

• Environmentally friendly: dsRNA degrades quickly in nature and does not contaminate soil or water.

• Safe for humans and animals: RNA molecules are easily degraded in the digestive system.

• Reduces pest resistance: RNAi allows gene-target rotation, making it harder for pests to develop resistance.

Challenges in RNAi Application

Despite its advantages, several biological challenges must be addressed:

• dsRNA is easily degraded by digestive enzymes
  the alkaline pH of insect midguts (especially in Lepidoptera) accelerates dsRNA breakdown
• dsRNA absorption differs among insect species
• dsRNA may become trapped in cells and fail to be processed into siRNA

These factors reduce RNAi effectiveness in certain insect orders. To improve RNAi performance, several innovations can be applied nanoparticles to protect dsRNA, symbiotic bacteria engineered to produce dsRNA inside insects, cationic liposomes to enhance cellular uptake, and engineered pathogenic fungi that deliver RNAi into the insect body.

RNA interference technology opens new opportunities for the development of dsRNA/siRNA-based biopesticides as a more specific and environmentally friendly alternative to conventional chemical pesticides. However, the success of RNAi-based products strongly depends on dsRNA stability, application methods, and the biological response of target pests. 

Therefore, laboratory testing is a critical step to ensure effectiveness and safety before field application. IML Testing and Research supports the development of RNAi-based biopesticides, including dsRNA/siRNA formulations and microbe-based RNAi products, through comprehensive laboratory testing services. 

These services include stability testing, biological efficacy testing against target pests, and evaluation of formulation quality and safety. Consult with IML Testing and Research to ensure your RNAi products are scientifically validated and ready for responsible application.

Author: Safira
Editor: Sabilla Reza

Reference:

Tong, H., Guan, R., Wang, F., Chen, H., Wang, L., & Liu, T. (2025). Prospects and challenges of RNA interference-based technologies for insect pest control. Current Opinion in Insect Science, 72, 100–123.