RNAi-mediated knockdown of the voltage gated sodium ion channel TcNav causes mortality in Tribolium castaneum

Abstract

The voltage-gated sodium ion channel (VGSC) belongs to the largest superfamily of ion channels. Since VGSCs play key roles in physiological processes they are major targets for effective insecticides. RNA interference (RNAi) is widely used to analyse gene function, but recently, it has shown potential to contribute to novel strategies for selectively controlling agricultural insect pests. The current study evaluates the delivery of dsRNA targeted to the sodium ion channel paralytic A (TcNav) gene in Tribolium castaneum as a viable means of controlling this insect pest. Delivery of TcNav dsRNA caused severe developmental arrest with larval mortalities up to 73% post injection of dsRNA. Injected larvae showed significant (p < 0.05) knockdown in gene expression between 30–60%. Expression was also significantly (p < 0.05) reduced in pupae following injection causing 30% and 42% knockdown for early and late pupal stages, respectively. Oral delivery of dsRNA caused dose-dependant mortalities of between 19 and 51.34%; this was accompanied by significant (p < 0.05) knockdown in gene expression following 3 days of continuous feeding. The majority of larvae injected with, or fed, dsRNA died during the final larval stage prior to pupation. This work provides evidence of a viable RNAi-based strategy for insect control.

Knockdown of nuclease activity in the gut enhances RNAi efficiency in the Colorado potato beetle, Leptinotarsa decemlineata , but not in the desert locust, Schistocerca gregaria

“…Interestingly, a clear response could not be observed, suggesting that no potent environmental RNAi response exists in our lab strain of T. castaneum. It is noteworthy that this discrepancy was also mentioned by another recently published research paper (Miyata et al, 2014), while another research group more recently succeeded in delivering dsRNA through the diet of T. castaneum (Abd El Halim et al, 2016). This indicates that the ability to generate a potent environmental RNAi response in T.…”

Targeting the potassium ion channel genes SK and SH as a novel approach for control of insect pests: efficacy and biosafety

“…In the present study the LC 50 values for mortality for larvae injected with SK and SH dsRNA were 2.39 and 34.93 ng larva –1 , respectively, compared to 65 and 117.01 ng mg –1 diet 6 days post‐delivery by feeding. This compares with LC 50 values of 79.89 ng larva –1 by injection and 150.23 ng mg –1 by feeding at day 6 in response to targeting the TcNa v gene in T. castaneum . In contrast, oral delivery of dsRNA targeted against calcium channel genes via an RNAi‐based approach failed to induce mortality in T. castaneum .…”

“…Current insecticides most commonly target the insect nervous system, often targeting the ion channels responsible for perpetuating the action potential along neurons and the enzymes of the synaptic cleft responsible for the degradation of neurotransmitters. Recent studies have shown that targeting the voltage‐gated sodium channels, a primary target for pyrethroids, using RNAi caused approximately 80% adult mortality of T. castaneum . The potassium ion channels also represent viable targets for RNAi.…”

“…Recent studies have shown that targeting the voltage-gated sodium channels, a primary target for pyrethroids, using RNAi caused approximately 80% adult mortality of T. castaneum. 28 The potassium ion channels also represent viable targets for RNAi. They are composed of two parts: the filter, which allows potassium ions to pass, and the gate, which opens and closes the channel depending on environmental signals.…”

Implementing the sterile insect technique with RNA interference – a review

“…In this context, the development of new methods for insect control is of key importance and there has been intense interest in the utility of gene silencing methods induced by RNA interference (RNAi). RNAi can induce mortality (Yang & Han, ; Cao et al., ; Abd El Halim et al., ; Christiaens et al., ; Hu et al., ; Malik et al., ), create beneficial phenotypes for insect control (Salvemini et al., ; Shukla & Palli, ; Peng et al., ; Yu et al., ), and prevent pesticide resistance in insect pests (Figueira‐Mansur et al., ; Guo et al., ; Wei et al., ; Bona et al., ; Sandoval‐Mojica & Scharf, ). Therefore, the potential for RNAi as a basis for future pest management strategies holds great promise (Huvenne & Smagghe, ; Gu & Knipple, ; Scott et al., ; Baum & Roberts, ; Kim et al., ).…”