RNAi-Based Functional Genomics in Hemiptera

Abstract

RNA interference (RNAi) is a powerful approach for sequence-specific gene silencing, displaying tremendous potential for functional genomics studies in hemipteran insects. Exploiting RNAi allows the biological roles of critical genes to be defined and aids the development of RNAi-based biopesticides. In this review, we provide context to the rapidly expanding field of RNAi-based functional genomics studies in hemipteran insects. We highlight the most widely used RNAi delivery strategies, including microinjection, oral ingestion and topical application. Additionally, we discuss the key variables affecting RNAi efficacy in hemipteran insects, including insect life-stage, gene selection, the presence of nucleases, and the role of core RNAi machinery. In conclusion, we summarise the application of RNAi in functional genomics studies in Hemiptera, focusing on genes involved in reproduction, behaviour, metabolism, immunity and chemical resistance across 33 species belonging to 14 families.

RNAi-Mediated Silencing of the Chitinase 5 Gene for Fall Webworm (Hyphantria cunea) Can Inhibit Larval Molting Depending on the Timing of dsRNA Injection

“…The RNAi efficiency and the resulting phenotypes were variable in the target insect. These variations are reliant on several critical factors, such as the target gene transcript abundance, spatial and temporal expression profiles, and the protein stability and turnover rate of the target gene [ 33 , 34 ]. In H. cunea , we found that HcCht5 was highly expressed during molting, while its expression decreased by about 40–60 times during inter-molting ( Figure 2 C), suggesting the function of HcCht5 in the molting process.…”

Current scenario of RNAi‐based hemipteran control

“…Each method has advantages and disadvantages with respect to the required experimental logistics. For a discussion of traditionally used delivery methods, readers are directed to a recently published review 9 . Upon entry into the insect, one of the first requirements for initiating the RNAi mechanism is the presence of a functional RNAi machinery (Fig.…”

Optimizing Efficient RNAi-Mediated Control of Hemipteran Pests (Psyllids, Leafhoppers, Whitefly): Modified Pyrimidines in dsRNA Triggers

“…RNAi-based studies in whiteflies show significant knockdown of a wide set of gene targets, with reviews by Kaur et al (2020) [119], Luo et al (2017) [24] and others (e.g., and references therein: [120][121][122][123][124][125][126][127][128]. The earliest RNAi in whitefly, B. tabaci, used dsRNA's of actin, BtSnap and chickadee [129].…”

“…The majority of leafhoppers and planthoppers of economic importance are in the same taxonomic suborder Auchenorrhyncha [ 137 ]. Reviews on RNAi in hemipterans show increasing research and development across a growing number of these important leafhopper and planthopper vectors [ 123 , 138 , 139 ]. Examples include the Green Rice Leafhopper, Nephotettix cincticeps; laccase-2 gene knockdown in first instar nymphs [ 140 ].…”

“…Even though there are many published studies using exogenous RNAi to significantly reduce insect vectors, including many reports of gene target suppression after ingestion of dsRNA by most plant-feeding hemipterans, such as the examples above, and in the following reviews (e.g., and references therein: [ 49 , 57 , 58 , 123 , 138 , 139 ], there is a need to optimize the RNAi activity to maximize efficacy, so that the concentration and cost per treatment can be reduced.…”