Characterization and expression patterns of key ecdysteroid biosynthesis and signaling genes in a spider mite (Panonychus citri)

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Scientists have made significant progress in understanding and unraveling several aspects of double-stranded RNA (dsRNA)-mediated gene silencing during the last two decades. Now that the RNA interference (RNAi) mechanism is well understood, it is time to consider how to apply the acquired knowledge to agriculture and crop protection. Some RNAi-based products are already available for farmers and more are expected to reach the market soon. Tailor-made dsRNA as an active ingredient for biopesticide formulations is considered a raw material that can be used for diverse purposes, from pest control and bee protection against viruses to pesticide resistance management. The RNAi mechanism works at the messenger RNA (mRNA) level, exploiting a sequence-dependent mode of action, which makes it unique in potency and selectivity compared with conventional agrochemicals. Furthermore, the use of RNAi in crop protection can be achieved by employing plant-incorporated protectants through plant transformation, but also by non-transformative strategies such as the use of formulations of sprayable RNAs as direct control agents, resistance factor repressors or developmental disruptors. In this review, RNAi is presented in an agricultural context (discussing products that have been launched on the market or will soon be available), and we go beyond the classical presentation of successful examples of RNAi in pest-insect control and comprehensively explore its potential for the control of plant pathogens, nematodes and mites, and to fight against diseases and parasites in beneficial insects. Moreover, we also discuss its use as a repressor for the management of pesticide-resistant weeds and insects. Finally, this review reports on the advances in non-transformative dsRNA delivery and the production costs of dsRNA, and discusses environmental considerations.

Section: Rnai Applications In Pest Managementmentioning

confidence: 99%

RNA interference technology in crop protection against arthropod pests, pathogens and nematodes

Zotti

Santos

Cagliari

et al. 2018

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243

“…A) and stem leaf‐mediated (Fig. C) methods were developed and proven to be successful in T. urticae , T. cinnabarinus and P. citri . Leaf disc (leaf coating)‐ and immersion (soaking)‐mediated RNAi (Fig.…”

Section: Efficiency Of Rna In Various Mite Speciesmentioning

confidence: 99%

“…mu‐class glutathione S‐transferase and carboxylesterase ), and this in turn resulted in increased susceptibility to acaricides . Through silencing of two essential development‐related genes, chitinase (involved in chitin degradation and reconstruction) and Spook (a Halloween ecdysteroid hormone‐synthesizing gene), mortality rates of 80.1 and 40%, respectively, at 72 h after the feeding of dsRNA could be observed in P. citri mites as a consequence of failure of molting and the mites being trapped in the old cuticle . The tested RNAi targets in mites, listed in Table , could be further evaluated as candidates for mite control, especially those resulting in high mortality ( coatomer subunit epsilon genes , chitinase , etc.)…”

Section: Efficiency Of Rna In Various Mite Speciesmentioning

confidence: 99%

“…After uptake of dsRNA from the environment, gene silencing can be achieved in cells, and if this dsRNA‐induced gene‐silencing signal can be transported from one cell to another nearby cell or from one tissue to another (distant) tissue, then systemic RNAi in the whole organism may be achieved . A study investigating silencing of the chitinase gene and a Halloween gene in spider mites suggests that there is systemic transport of dsRNA (or the gene‐silencing signal) from the tissue that was exposed to the dsRNA (gut) to more distant tissues, such as the cuticle, hemolymph and prothoracic glands. In addition, a study investigating the spread of injected fluorescently labeled dsRNA and siRNA molecules in T. urticae revealed a systemic distribution of these small RNAs in the whole mite body.…”

Section: Possible Factors That Enhance Systemic Movement Of Rna In MImentioning

confidence: 99%

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Beyond insects: current status and achievements of RNA interference in mite pests and future perspectives

Niu

Shen

Christiaens

et al. 2018

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Mites comprise a group of key agricultural pests on a wide range of crops. They cause harm through feeding on the plant and transferring dangerous pathogens, and the rapid evolution of pesticide resistance in mites highlights the need for novel control methods. Currently, RNA interference (RNAi) shows great potential for insect pest control. Here, we review the literature regarding RNAi in mite pests. We discuss different target genes and RNAi efficiency in various mite species, a promising Varroa control program using RNAi, the synergy of RNAi with plant defense mechanisms and microorganisms, and current understanding of systemic movement of double-stranded RNA (dsRNA). On the basis of this evidence, we can conclude that there is clear potential for application of RNAi-based mite control, but further research on several aspects of RNAi in mites is needed, including: (i) the factors influencing RNAi efficiency, (ii) the mechanism of environmental RNAi and cross-kingdom dsRNA trafficking, (iii) the mechanism of possible systemic and parental RNAi, and (iv) non-target effects, specifically in predatory mites, which should be considered during RNAi target selection. © 2018 Society of Chemical Industry.

“…This method was used to characterize the functions of genes encoding cathepsin D, chitin synthase, and the inhibitor of apoptosis in Diaphorina citri . This method was also used in RNAi target selection in the spider mites Tetranychus urticae and Pononychus citri . The plant‐leaf mediated dsRNA uptake method mimics a natural feeding status of aphids.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a cuticle protein gene as a potential RNAi target in aphids

Shang

Ding

et al. 2019

BACKGROUND RNA interference (RNAi) has potential as a pest insect control technique. One possible RNAi target is the cuticle protein, which is important in insect molting and development. As an example, here we evaluate the possibility of designing double‐stranded RNA (RNA) that is effective for silencing the cuticle protein 19 gene (CP19) in aphids but is harmless to non‐target predator insects. RESULTS The sequences of CP19s were similar (86.6–94.4%) among the tested aphid species (Aphis citricidus, Acyrthosiphon pisum, and Myzus persicae) but different in the predator Propylaea japonica. Ingestion of species‐specific dsRNAs of CP19 by the three aphids produced 39.3–64.2% gene silencing and 45.8–55.8% mortality. Ingestion of non‐species‐specific dsRNA (dsAcCP19) by Ac. pisum and M. persicae gave gene silencing levels ranging from 40.4% to 50.3% and 43.3–50.8% mortality. The dsApCP19 did not affect PjCP19 expression or developmental duration in P. japonica. CONCLUSION The results demonstrate that CP19 is a promising RNAi target for aphid control via one dsRNA design. The targeting of genes that are conserved in insect pests but not present in beneficial insects is a useful RNAi‐based pest control strategy. © 2019 Society of Chemical Industry