Increased virulence in the locust‐specific fungal pathogen Metarhizium acridum expressing dsRNAs targeting the host F1F0‐ATPase subunit genes

Low RNA interference (RNAi) efficiency in many insect pests has significantly prevented its widespread application for insect pest management. This article provides a comprehensive review of recent research in developing various strategies for enhancing RNAi efficiency. Our review focuses on the strategies in target gene selection and double‐stranded RNA (dsRNA) delivery technologies. For target gene selection, genome‐wide or large‐scale screening strategies have been used to identify most susceptible target genes for RNAi. Other strategies include the design of dsRNA constructs and manipulate the structure of dsRNA to maximize the RNA efficiency for a target gene. For dsRNA delivery strategies, much recent research has focused on the applications of complexed or encapsulated dsRNA using various reagents, polymers, or peptides to enhance dsRNA stability and cellular uptake. Other dsRNA delivery strategies include genetic engineering of microbes (e.g. fungi, bacteria, and viruses) and plants to produce insect‐specific dsRNA. The ingestion of the dsRNA‐producing organisms or tissues will have lethal or detrimental effects on the target insect pests. This article also identifies obstacles to further developing RNAi for insect pest management and suggests future avenues of research that will maximize the potential for using RNAi for insect pest management. © 2021 Society of Chemical Industry

Section: Strategies For Enhancing Rnai Efficiencymentioning

confidence: 99%

Strategies for enhancing the efficiency of RNA interference in insects

Silver

Cooper

Zhu

2021

“…Application of RNAi‐mediated pest control relies on a stable dsRNA delivery system. Some delivery systems have been suggested to be effective in pest control, including genetic modification of host plants, use of bacterial, viral, and or fungal agents, as well as potentially direct feeding and/or spray applications of dsRNA . Similar to what has been shown in other insects, LmIAP1 has the potential to be developed for locust control through these dsRNA delivery systems.…”

Section: Discussionmentioning

confidence: 99%

“…The utilization of chemical pesticides in locust control has been recognized as being unsustainable for safeguarding various ecosystems. Expression of an insect toxin or host targeting dsRNA in wild‐type insect pathogenic fungi have been confirmed as promising strategies to improve the speed of kill of Metarhizium to locust. These findings indicate that continued research in locust control is needed and our data show that use of synergistic strategies that combine different approaches can yield a more effective product that may ultimately reduce costs, improve efficiency and persistence, and increase agricultural sustainability.…”

Section: Discussionmentioning

confidence: 99%

Inhibitor of apoptosis‐1 gene as a potential target for pest control and its involvement in immune regulation during fungal infection

Zhang

Keyhani

Zhang

et al. 2020

Self Cite

BACKGROUND Environmentally friendly insect management technologies, including RNA interference (RNAi) and entomopathogenic fungi, have attracted increasing attention as options for pest control. Here, we sought to extend RNAi‐directed targeting of the inhibitor of apoptosis protein 1 (IAP1) gene to the locust, and to examine its relationship to immune responses and susceptibility to Metarhizium acridum, a locust‐specific fungal pathogen. RESULTS Expression of the locust LmIAP gene was induced in the hemolymph and fat body after M. acridum infection. RNAi‐directed silencing of locust LmIAP1 resulted in increased caspase 3 activity, degeneration of the gut and dose‐dependent mortality. Synergistic mortality was seen in RNAi‐LmIAP/fungal co‐infection experiments with median survival time (MST) values decreasing from ∼ 5 days for RNAi and M. acridum treatments alone, to 2.6 days for co‐treatments. Reduced hemocyte numbers and antimicrobial peptide levels were seen in co‐treated locusts, with changes in gut opportunistic pathogenic bacteria seen between treatments. Enhanced fungal sporulation on co‐treated insect cadavers was also compared with fungal infection alone. CONCLUSIONS Silencing of the locust LmIAP1 gene results in direct mortality and increases insect susceptibility to insect fungal pathogens, in part by decreasing immunity and altering the gut microbiome. © 2019 Society of Chemical Industry

“…Methods including nanoparticles, transfection reagents and dsRNA encapsulation using bacteria or plastids are potential techniques to increase dsRNA stability. Transferring or delivery of the dsRNA of a target gene into a plant, virus and/or fungal pathogen that would in turn ‘deliver’ the dsRNA to the target insect has been demonstrated in several cases, and a similar approach can now be used regarding nxf1 .…”

Section: Discussionmentioning

confidence: 99%

“…Recently it has been shown that the virulence of an insect pathogen can be improved via expression of a dsRNA targeting the insect F1F0‐ATPase subunit gene. These studies indicate that expression in the locust‐specific fungal pathogen Metarhizium acridum offers a means of dsRNA delivery to locusts . Engineering of these fungal pathogens has shown significant potential in targeted pest control, including for vectors of human disease‐causing agents such as mosquitoes .…”

Section: Introductionmentioning

confidence: 99%

RNAi‐knockdown of the Locusta migratoria nuclear export factor protein results in insect mortality and alterations in gut microbiome

Xie

Zhang

et al. 2018

Self Cite

BACKGROUND: The migratory locust Locusta migratoria is one of the most important agricultural pests worldwide. The nuclear export factor 1 (NXF1) protein plays a crucial role in mediating mRNA transport from the nucleus to the cytoplasm. This study evaluates whether NXF1 could be a potential target for RNAi-mediated pest control of L. migratoria. RESULTS:We cloned and characterized the nuclear export factor lm-nxf1 of L. migratoria. Lm-nxf1 was expressed in all tissues examined, including head, fat body, hemolymph, trunk, leg and midgut, with high expression observed in the hemolymph and fat body. Injection of lm-nxf1 dsRNA into hemolymph resulted in inhibition of mRNA export in hemocytes, which were used as a target for observing mRNA export. Total hemocyte levels were reduced by ca. 97% in lm-nxf1-dsRNA-treated locusts, and high insect mortality occurred with LT 50 = 7.75 day as compared with 18.15 day for gfp-dsRNA-treated controls. Further, the locust intestine became atrophy, and the opportunistic pathogens Enterobacter aerogenes, Klebsiella pneumoniae and Enterobacter asburiae were specifically detected in midgut after lm-nxf1 dsRNA treatment. CONCLUSIONS:The results reveal that knockdown of the lm-nxf1 gene affects the survival of L. migratoria, indicating that lm-nxf1 is a potential target for RNAi-mediated pest control.