dsRNAs Targeted to the Brown Planthopper Nilaparvata lugens: Assessing Risk to a Non-Target, Beneficial Predator, Cyrtorhinus lividipennis

Abstract

RNA interference (RNAi) technology is becoming a maturing insect management approach. Before commercial-scale application, however, it is necessary to assess risks to non-target organisms (NTOs). Here, we evaluated the influence of RNAi technology, targeted to the brown planthopper (BPH, Nilaparvata lugens, Hemiptera: Delphacidae), a serious pest of Asian rice cropping systems, by dsRNA feeding. Three dsRNA fragments, targeting sodium channel protein Nach-like (dsNlNa), autophagy protein 5 (dsNlAup5), and V-type proton ATPase catalytic subunit A (dsNlvATP-A), which were highly lethal to BPH, were selected to evaluate their effects on an important predator of BPH, Cyrtorhinus lividipennis (Hemiptera: Miridae). It showed that these three dsRNA fragments posed no risks to C. lividipennis at worst-case treatments when fed with high concentrations (10×) dsRNAs. These findings not only establish part of a risk assessment protocol for RNAi-based products on NTOs but also contribute to the development and deployment of new technologies for BPH management.

RNAi-Based Biopesticides Against 28-Spotted Ladybeetle Henosepilachna vigintioctopunctata Does Not Harm the Insect Predator Propylea japonica

“…However, ds HvHel25E and ds HvSpr54k did not affect P. japonica at either the transcriptional or the organismal level, showing that ds HvHel25E and ds HvSpr54k had negligible effects on P. japonica . This finding is consistent with the previous findings of the risk assessment studies, including ds NlvATP-A on the Nilaparvata lugens predator, Cyrtorhinus lividipennis . Similarly, feeding on a high concentration of Euschistus heros -active dsRNA did not lead to adverse effects on the survival or parasitism capacity of the parasitoid wasp Telenomus podisi , even though there were 17–21 nt matches between them .…”

“…One recent study revealed that, in T. castaneum , RNAi could be effectively triggered by the segment matches of ≥16 or >26 nt . Therefore, during the process of designing and developing dsRNA fragments, certain bioinformatics approaches could be utilized to reduce the probability of negative effects occurring in NTOs. ,, In this study, bioinformatics analysis showed that the aligned sequence of HvHel25E , HvSrp54k , and HvProsbeta6 had 11, 21, and 4–21 nt matches in the dsRNA region to P. japonica , and none for HvProsbeta5 , HvProalpha6 , and HvABCH1 . Therefore, HvHel25E and HvSrp54k were selected for the NTOs risk assessment.…”

“…This finding is consistent with the previous findings of the risk assessment studies, including dsNlvATP-A on the Nilaparvata lugens predator, Cyrtorhinus lividipennis. 51 Similarly, feeding on a high concentration of Euschistus heros-active dsRNA did not lead to adverse effects on the survival or parasitism capacity of the parasitoid wasp Telenomus podisi, even though there were 17−21 nt matches between them. 53 Although the predictions based on gene sequence information can be used to avoid some potential risks to NTOs, other factors, including the degree of RNAi sensitivity among NTOs, concentration of the exposed dsRNA, dsRNA degradation conditions, the position of mismatches within the siRNA sequence, and the position of the dsRNA within the off-target could affect the result of the risk assessments of dsRNAs.…”

RNA Interference-Screening of Potentially Lethal Gene Targets in the White-Backed Planthopper Sogatella furcifera via a Spray-Induced and Nanocarrier-Delivered Gene Silencing System

“…Additionally, at least one example has shown that the pest target gene dsRNAs have no gene silence effects on economic insect or WBPH predatory insect species, indicating the biosafety of the dsRNA pest control approach: dsRNAs with concentrations at 10 times than the LC 50 of dsRNA targeting BPH neither affected the predatory enemyCyrtorhinus lividipennis survival rates nor mRNA relative expression. 43 The utilization of nanoparticles can enhance the persistence of dsRNA in plants and provide the stability of dsRNA in an uncontrolled environment. 1 In this study, the nanomaterial SPc used has low cytotoxicity and is an important parameter for an ideal dsRNA vector.…”

Transcript Level and Sequence Matching Are Key Determinants of Off-Target Effects in RNAi

“…castaneum to nontarget species. Actually, our primary concern is that in the future, when RNAi technology is employed, dsRNA may result in toxicity to beneficial organisms through sequence-based effects, such as honeybees and the predatory natural enemies of insects. , If dsRNA is utilized to prevent and manage parasitic mites like Varroa destructor in bees, further research and exploration are essential to guarantee that bees are not adversely impacted by sequence-based effects of dsRNA while targeting the Varroa destructor. Therefore, while ensuring the efficacy of dsRNA in controlling pests, it is also important to ensure that beneficial organisms lack sequence-based effects.…”