Testing insecticidal activity of novel chemically synthesized siRNA against Plutella xylostella under laboratory and field conditions

PLoS One. 2013 May 7;8(5):e62990. doi: 10.1371/journal.pone.0062990. Print 2013.

Abstract

Background: Over the last 60 years, synthetic chemical pesticides have served as a main tactic in the field of crop protection, but their availability is now declining as a result of the development of insect resistance. Therefore, alternative pest management agents are needed. However, the demonstration of RNAi gene silencing in insects and its successful usage in disrupting the expression of vital genes opened a door to the development of a variety of novel, environmentally sound approaches for insect pest management.

Methodology/principal findings: Six small interfering RNAs (siRNAs) were chemically synthesized and modified according to the cDNA sequence of P. xylostella acetylcholine esterase genes AChE1 and AChE2. All of them were formulated and used in insecticide activity screening against P. xylostella. Bioassay data suggested that Si-ace1_003 and Si-ace2_001 at a concentration of 3 µg cm(-2) displayed the best insecticidal activity with 73.7% and 89.0%, mortality, respectively. Additional bioassays were used to obtain the acute lethal concentrations of LC50 and LC90 for Si-ace2_001, which were 53.66 µg/ml and 759.71 µg/ml, respectively. Quantitative Real-time PCR was used to confirm silencing and detected that the transcript levels of P. xylostella AChE2 (PxAChE2) were reduced by 5.7-fold compared to the control group. Consequently, AChE activity was also reduced by 1.7-fold. Finally, effects of the siRNAs on treated plants of Brassica oleracea and Brassica alboglabra were investigated with different siRNA doses. Our results showed that Si-ace2_001 had no negative effects on plant morphology, color and growth of vein under our experimental conditions.

Conclusions: The most important finding of this study is the discovery that chemically synthesized and modified siRNA corresponding to P. xylostella AChE genes cause significant mortality of the insect both under laboratory and field conditions, which provides a novel strategy to control P. xylostella and to develop bio-pesticides based on the RNA interference technology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholinesterase / deficiency
  • Acetylcholinesterase / genetics
  • Animals
  • Biological Assay*
  • Brassica / genetics
  • Chemistry Techniques, Synthetic
  • Gene Expression Regulation, Enzymologic / genetics
  • Laboratories*
  • Moths / enzymology
  • Moths / genetics*
  • Pest Control, Biological / methods*
  • RNA Interference
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / adverse effects
  • RNA, Small Interfering / chemical synthesis*
  • RNA, Small Interfering / genetics*

Substances

  • RNA, Messenger
  • RNA, Small Interfering
  • Acetylcholinesterase

Grants and funding

We thank the National Nature Science Foundation, People’s Republic of China for funding this work under grant no. 31171870. The authors also thank the Guangdong Province guided program of university industry cooperation (2010B090400138). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.