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

Abstract

BACKGROUND Potassium ion channels play a critical role in the generation of electrical signals and thus provide potential targets for control of insect pests by RNA interference. RESULTS Genes encoding the small conductance calcium‐activated potassium channel (SK) and the voltage‐gated potassium channel (SH) were knocked down in Tribolium castaneum by injection and oral delivery of dsRNA (dsTcSK and dsTcSH, respectively). Irrespective of the delivery mechanism a dose‐dependent effect was observed for knockdown (KD) of gene expression and insect mortality for both genes. Larvae fed a 400 ng dsRNA mg–1 diet showed significant gene (P < 0.05) knockdown (98% and 83%) for SK and SH, respectively, with corresponding mortalities of 100% and 98% after 7 days. When injected (248.4 ng larva–1), gene KD was 99% and 98% for SK and SH, causing 100% and 73.4% mortality, respectively. All developmental stages tested (larvae, early‐ and late‐stage pupae and adults) showed an RNAi‐sensitive response for both genes. LC50 values were lower for SK than SH, irrespective of delivery method, demonstrating that the knockdown of SK had a greater effect on larval mortality. Biosafety studies using adult honeybee Apis mellifera showed that there were no significant differences either in expression levels or mortality of honeybees orally dosed with dsTcSK and dsTcSH compared to control‐fed bees. Similarly, there was no significant difference in the titre of deformed wing virus, used as a measure of immune suppression, between experimental and control bees. CONCLUSION This study demonstrates the potential of using RNAi targeting neural receptors as a technology for the control of T. castaneum. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bacteria‐mediated RNAi for managing fall webworm, Hyphantria cunea: screening target genes and analyzing lethal effect

“…The selection of suitable species-specific target genes is an important initial step in developing effective RNAi-based control strategies. 38 In this study, we selected 23 candidate genes previously reported as effective RNAi targets in T. castaneum, 32,33 Spodoptera exigua, 34 Diaphorina citri 35 and Heortia vitessoides. 36 Surprisingly, of the 23 genes whose knockdown caused significant mortality in other insects, 70% of candidates caused less than 15% mortality, and only three induced more than 50% mortality in H. cunea larvae in the initial screening (Table 1).…”

“…In total, 23 genes were selected as candidate targets from Coleoptera, Lepidoptera, and Hemiptera insects (Table 1): 19 of which were previously reported for top mortality in T. castaneum 32,33 and 4 were reported for effective control in other insects such as Spodoptera exigua, 34 Diaphorina citri, 35 and Heortia vitessoides. 36 H. cunea homologous genes were detected in the H. cunea transcriptome database using the local BLAST program.…”

“…wileyonlinelibrary.com/journal/ps 32,33 Spodoptera exigua (Lepidoptera), 34 Diaphorina citri (Hemiptera), 35 and Heortia vitessoides (Lepidoptera). calculated.…”

Identification and pharmacological characterization of the voltage‐gated potassium channel Shab in diamondback moth, Plutella xylostella

“…However, compared with the extensive and long-term studies on sodium channels, only a few entomological studies have focused on Kv channels and regarded them as molecular targets for insecticide development. 6,16,32 In this study, we concentrated on Shab (Kv2) channel and cloned the Shab gene from P. xylostella for the first time. Consistent with the D. melanogaster and A. aegypti, 33 there is only one Shab gene (LOC105386449) in the P. xylostella genome.…”

Crosstalk among Indoleamines, Neuropeptides and JH/20E in Regulation of Reproduction in the American Cockroach, Periplaneta americana

“…We also injected dsGFP into cockroaches and found no effect on aaNAT transcription (results not shown). However, in view of recently reported off-target effects of dsGFP injection (impairing its host's core biological functions via affecting several genes implicated in central metabolic and developmental processes associated with RNA processing and transport, hormone metabolism, immunity and response to external stimulus and to stress) to control for nonspecific side effects of RNAi [33,34], we favored water as a control for RNAi, alone, as a widely used accepted approach in RNAi studies in insects [35,36].…”