New Spray Method Improves Control of Greenhouse Pests

Jim Crocker
14th August, 2024

New Spray Method Improves Control of Greenhouse Pests

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Andong National University, Korea, found that targeting the Snf7 gene with RNAi is as effective as targeting the vATPase gene in controlling western flower thrips
  • They identified dsRNA-degrading enzymes in the thrips that reduce RNAi effectiveness and suggested ways to mitigate their impact
  • Encapsulating dsRNA with chitosan significantly improved its stability and control efficacy, achieving 82.4% effectiveness in greenhouse tests compared to 59.2% with unprotected dsRNA
The western flower thrips, Frankliniella occidentalis, is a significant agricultural pest that causes direct feeding damage and transmits the tomato spotted wilt virus. Traditional chemical insecticides are becoming less effective due to increasing resistance, necessitating alternative control strategies. Recent research from Andong National University, Korea, has explored the use of RNA interference (RNAi) to target this pest[1]. RNAi is a biological process where RNA molecules inhibit gene expression, effectively silencing specific genes. This technique has shown promise in pest control due to its target specificity[2]. However, RNAi's effectiveness in field conditions has been inconsistent, partly due to environmental factors and RNA-degrading enzymes in the pests[2][3]. The study aimed to improve RNAi efficacy against F. occidentalis by exploring three strategies. First, researchers identified a more efficient RNAi target by comparing dsRNA specific to the Snf7 gene with dsRNA targeting the vacuolar-type ATPase (vATPase) gene. Both targets demonstrated similar effectiveness in controlling the thrips, indicating that Snf7 is a viable alternative target. Second, the study investigated the role of dsRNA-degrading enzymes in diminishing RNAi efficacy. These enzymes break down dsRNA, reducing its effectiveness. By annotating these enzymes and understanding their physiological roles, researchers could identify ways to mitigate their impact. Previous studies have highlighted the challenges posed by dsRNases and other barriers to RNAi efficiency[2]. This study builds on that knowledge by providing specific insights into the enzymes involved in F. occidentalis. Third, to protect dsRNA from degradation and enhance its stability under field conditions, the researchers encapsulated it with chitosan. Chitosan is a biopolymer that can protect dsRNA from environmental stressors like ultraviolet light and digestive enzymes in the thrips' gut. This encapsulation method draws from earlier work that demonstrated the potential of chitosan-based nanoparticles in protecting and delivering dsRNA effectively[3]. The encapsulated dsRNA was tested on F. occidentalis infesting hot peppers in a greenhouse. The results were promising, showing an 82.4% control efficacy compared to 59.2% with naked dsRNA. This significant improvement underscores the potential of chitosan encapsulation in enhancing RNAi-based pest control measures. Moreover, the study expanded the control spectrum by combining dsRNAs specific to three different thrips species. This mixture showed no adverse effects on non-target insects like Spodoptera exigua, indicating that the approach is both effective and environmentally friendly. This aligns with previous findings that emphasize the importance of target specificity in RNAi-based pest control[2][4]. In conclusion, the study from Andong National University demonstrates that chitosan-encapsulated dsRNA can significantly improve RNAi efficacy against F. occidentalis under field conditions. By identifying efficient RNAi targets, understanding the role of dsRNA-degrading enzymes, and using chitosan encapsulation, the researchers have addressed key challenges in RNAi-based pest control. This approach not only enhances control efficacy but also broadens the spectrum of control against multiple thrips species without harming non-target insects, paving the way for more sustainable and effective pest management strategies.

AgricultureBiotechPlant Science

References

Main Study

1) Spraying dsRNA with chitosan formulation improves control of the western flower thrips, Frankliniella occidentalis, in a greenhouse.

Published 13th August, 2024

https://doi.org/10.1111/imb.12954

Related Studies

2) Molecular mechanisms influencing efficiency of RNA interference in insects.

https://doi.org/10.1002/ps.5126

3) Development of CS-TPP-dsRNA nanoparticles to enhance RNAi efficiency in the yellow fever mosquito, Aedes aegypti.

https://doi.org/10.1038/s41598-019-45019-z

4) Off-target effects of RNAi correlate with the mismatch rate between dsRNA and non-target mRNA.

https://doi.org/10.1080/15476286.2020.1868680


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