Developmental control of a lepidopteran pest Spodoptera exigua by ingestion of bacteria expressing dsRNA of a non-midgut gene.
BACKGROUND
RNA interference (RNAi) induced through double stranded RNA (dsRNA) has been used widely to study gene function in insects. Recently, it has been reported that gene knockdown in several insects can be induced successfully through feeding with dsRNA. However, it is still unknown whether phenotypic silencing of genes not expressed in the midgut occurs after ingestion of insect dsRNA.


RESULTS
Using chitin synthase gene A (SeCHSA) as the target gene, which is expressed in the cuticle and tracheae of the lepidopteran pest Spodoptera exigua, we showed that the growth and development of S. exigua larvae fed Escherichia coli expressing dsRNA of SeCHSA was disturbed, resulting in lethality. In the 4th and 5th larval instars, prepupae, and pupae, the mean survival rates of insects fed the dsRNA-containing diet were 88.64%, 74.24%, 68.43% and 62.63% respectively. The survival rates in the 5th instar larvae, prepupae and pupae stages were significantly lower than those of all controls, and significant lethality differences were also found between dsSeCHSA treatment and dsControl or ddH(2)O control in the 4th instar larvae. The effects of ingesting bacterially expressed dsRNA on transcription of the target gene, tissue structure, and survival rates of insects were dose-dependent.


CONCLUSIONS
Our results suggest that SeCHSA dsRNA may be useful as a means of insect pest control.
Tian
Honggang
H
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
Peng
Han
H
Yao
Qiong
Q
Chen
Hongxin
H
Xie
Qi
Q
Tang
Bin
B
Zhang
Wenqing
W
D000818:Animals; D001419:Bacteria / Q000235:genetics*; D001483:Base Sequence; D002687:Chitin Synthase / Q000235:genetics; D005786:Gene Expression Regulation; D007814:Larva / Q000254:growth & development; D008969:Molecular Sequence Data; D010572:Pest Control, Biological; D010802:Phylogeny; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D018411:Spodoptera / Q000254:growth & development*
D012330:RNA, Double-Stranded; D002687:Chitin Synthase