Sublethal Endpoints in Non-target Organism Testing for Insect-Active GE Crops.

Andrew Roberts,Jörg Romeis,Richard L Hellmich,Fernando H Valicente,Xuguo Zhou,John L Teem,Thais B Rodrigues,Martin G Edwards,Ana M Vélez,Marina Mühl,Steven L Levine,Chad J Boeckman,Judith K Brown,Rachel L Melnick

doi:10.3389/fbioe.2020.00556

Abstract

Historically, genetically engineered (GE) plants that have incorporated genes conferring insect protection have primarily used Cry proteins derived from Bacillus thuringiensis (Bt) to achieve their insecticidal phenotype. As a result, regulators have developed a level of familiarity and confidence in reviewing plants incorporating these insecticidal proteins. However, new technologies have been developed that produce GE plants that incorporate pest protection by triggering an RNA interference (RNAi) response or proteins other than Bt Cry proteins. These technologies have new modes of action. Although the overall assessment paradigm for GE plants is robust, there are ongoing discussions about the appropriate tests and measurement endpoints needed to inform non-target arthropod assessment for technologies that have a different mode of action than the Bt Cry proteins. As a result, increasing attention is being paid to the use of sublethal endpoints and their value for environmental risk assessment (ERA). This review focuses on the current status and history of sublethal endpoint use in insect-active GE crops, and evaluates the future use of sublethal endpoints for new and emerging technologies. It builds upon presentations made at the Workshop on Sublethal Endpoints for Non-target Organism Testing for Non-Bt GE Crops (Washington DC, USA, 4–5 March 2019), and the discussions of government, academic and industry scientists convened for the purpose of reviewing the progress and status of sublethal endpoint testing in non-target organisms.

Highlights

The introduction of insect-resistant genetically engineered (GE) crops began in the 1990s, with a number of today’s crops incorporating Bacillus thuringiensis (Bt) Cry proteins (Koch et al, 2015; Naranjo et al, 2020)
In line with best practices for non-target organism (NTO) study design the criteria for selection of species to characterize the spectrum of activity of IPD072Aa was based on several factors such as the phylogenetic relationship between the species and WCR, established laboratory bioassay methodologies, availability of laboratory reared insects, a known suitable diet and reproducibility of the measurement endpoints (Boeckman et al, 2019)
The testing associated with any particular insect-active GE crop should be informed by a problem formulation process

Summary

INTRODUCTION

The introduction of insect-resistant GE crops began in the 1990s, with a number of today’s crops incorporating Bt Cry proteins (Koch et al, 2015; Naranjo et al, 2020). There are a number of reasons for this, including that it is normally unambiguous, easy to measure and has a clear and direct relationship to potential adverse effects on populations of NTOs and ecosystem services they provide Because it is a common endpoint, there are study designs and methods described for measuring mortality in multiple test systems and for many test species that are validated. In line with best practices for NTO study design (see NTO Study Design above) the criteria for selection of species to characterize the spectrum of activity of IPD072Aa was based on several factors such as the phylogenetic relationship between the species and WCR, established laboratory bioassay methodologies, availability of laboratory reared insects, a known suitable diet and reproducibility of the measurement endpoints (Boeckman et al, 2019). This knowledge related to its mode of action and the phylogentic relationship between the candidate surrogate species and WCR will guide

DISCUSSION

CONCLUSIONS

DISCLOSURE