Emerald Ash Borer Specific Gene Silencing Has No Effect on Non-target Organisms

Abstract

The sequence complementarity of the RNA interference (RNAi) pathway allows for targeted suppression of genes essential for insect survival, and enables development of pest management strategies specific to a given species while reducing the likelihood of adversely impacting non-target organisms (NTOs). The feasibility of manipulating the RNAi pathway to cause mortality in the highly invasive emerald ash borer (EAB) has been demonstrated. Here the spectrum of activity of three double stranded RNAs (dsRNAs) targeting the genes hsp, shi, and sn-rnp in EAB was evaluated in model insects representing five functional guilds including herbivore, predator, detritivore, pollinator, parasitoid; the last represented by the classical biological control agents currently deployed for EAB management in North America. All NTOs were exposed to EAB-specific dsRNAs in diet bioassays that measured potential lethal effects. Gene expression and in silico analysis were also assessed on NTOs for which gene sequences were publicly available. Bioassays demonstrated no lethal effects on our model insects, suggesting a narrow spectrum of activity for the three EAB-specific dsRNAs evaluated. The gene expression and in silico analyses suggest potential sublethal effects on our model pollinator; however we found no effects on insect survival. Overall, our results suggest no adverse effects of the RNAi strategy targeting EAB genes on the survival of the selected non-target organisms we evaluated. The results from this study provide guidance for future RNAi risk analyses that will allow this technology to move forward to a deployment stage.

Advances and Challenges in RNA Interference Technology for Citrus Huanglongbing Vector Control

“…siRNAs of approximately 21-25 nucleotides are the key intermediaries in triggering sequence-specific RNA degradation during PTGS in invertebrates [72]. These sequence specificities minimize any detrimental effects of RNAi on non-target organisms (NTOs) [74].…”

“…To date, however, there are methods to quantify the reliability of these bioinformatic software in assessing such off-target effects. Given the variability in environmental exposure, barriers to systemic exposure, and differences in RNAi machinery among organisms, the bioinformatic software as the sole tool is not recommended [74,76,77]. Specialists from the academic, industrial, and government sectors have discussed several aspects of RNAi, with particular focus on furthering our knowledge of the technology for risk assessment [18,78].…”

“…A recent study evaluated the activity of three specific dsRNA molecules targeting genes in different insects, representing the classic biocontrol agents of the emerald ash borer (EAB, Agrilus planipennis) in some countries. The study provided substantial data to demonstrate the feasibility of using novel alternatives for EAB management that are ecofriendly and safe for NTOs [74]. A recent study evaluated the activity of three specific dsRNA molecules targeting genes in different insects, representing the classic biocontrol agents of the emerald ash borer (EAB, Agrilus planipennis) in some countries.…”

“…A recent study evaluated the activity of three specific dsRNA molecules targeting genes in different insects, representing the classic biocontrol agents of the emerald ash borer (EAB, Agrilus planipennis) in some countries. The study provided substantial data to demonstrate the feasibility of using novel alternatives for EAB management that are ecofriendly and safe for NTOs [74].…”

First Sprayable Double-Stranded RNA-Based Biopesticide Product Targets Proteasome Subunit Beta Type-5 in Colorado Potato Beetle (Leptinotarsa decemlineata)

“…( Bachman et al, 2013 ) studied the specificity of dsSnf7 designed to target western corn rootworm ( Diabrotica virgifera virgifera ) and determined that insecticidal activity is limited to the insect subfamily. Another study evaluated off-target effects of three different dsRNAs targeting emerald ash borer ( Agrilus planipennis ) and showed high specificity to the target organism with no mortality and gene silencing observed on other insects from the same Coleoptera order, such as L. decemlineata and Coleomegilla maculata ( Pampolini and Rieske, 2020 ).…”